In the spring of 1997 someone began attacking elementary school children in the hillside neighborhoods of Suma Ward, in western Kobe. Five children were attacked between February and May. Ayaka Yamashita, a 10-year-old fourth-grader, died a week after being struck on the head with a hammer in March. Jun Hase, an 11-year-old sixth-grader, disappeared on May 24 and was found three days later; part of his body had been left at the gate of a public junior high school, with a note mocking the police. A letter to the local newspaper, the Kobe Shimbun, followed, signed with an invented name written in elaborate characters: 酒鬼薔薇聖斗, read as Sakakibara Seito.
On June 28, 1997, police arrested a 14-year-old third-year junior high school student who lived in the area. He confessed. Because of his age, Japanese law did not allow him to be prosecuted. His case went to the Kobe Family Court, which found him responsible for the attacks and, on October 17, 1997, sent him to a medical reformatory. He was released in 2004 and lives under a protected identity. He has never been criminally convicted of anything.
Japanese media have always referred to him as "Boy A" (shonen A), and the law forbids publishing anything that would identify him. This account follows that practice. It uses his own alias and the term "Boy A," and gives no name, address, photograph or other identifying detail.
The case is one of the most discussed crimes in modern Japan. It led directly to the first substantive revision of the Juvenile Act in half a century, which lowered the age at which juveniles can face criminal punishment from 16 to 14. Almost two decades later, it returned to the headlines when the former Boy A published a memoir, Zekka, without telling the families of the children he had killed.
Suma Ward lies along the western edge of Kobe, between the sea and the Rokko mountains. The attacks took place in tidy, middle-class residential districts on the hills behind the coast. The city was still rebuilding in 1997: the Great Hanshin earthquake of January 1995 had killed more than 6,000 people across the region and devastated Kobe, a city of about a million.
The boy who became known as Boy A was born in 1982. In 1997 he was 14 and in his third and final year of junior high school. Juvenile hearings in Japan are closed, and almost nothing about his upbringing has been made public through official channels. What is known comes mainly from the family court's published summary, from prosecutors and lawyers interviewed later, and from his own memoir. The family court summary describes a long history of escalating cruelty, first to animals and then to people, together with isolation, fantasies of killing and a strained relationship with his mother. The prosecutor who questioned him told the Kobe Shimbun in 2022 that the boy's killing of small animals had begun around the time his grandmother, a person who understood him, died.
The first attack was not reported in the press at the time. On February 10, 1997, the family court later found, the boy struck two sixth-grade girls, both aged 12, on the head with a hammer he carried in a bag. One of them needed about a week of treatment for a head injury. Neither girl is named here.
Ayaka Yamashita was 10 years old and in the fourth grade. Her family lived in Suma Ward: her father, Kenji, her mother, Kyoko, and her older brother, Kota, who was then in his first year of junior high school. Her family remember her as a lively child who loved animals and plants and who was grateful even to the shoes she wore. A drawing she made of a sneaker hangs in the family home, with a message to it in her handwriting: "Thanks for walking and running, you worked hard!!"
Kota, who was shy where his sister was outgoing, told the Kobe Shimbun in 2017, in his first interview, that the two of them often quarreled but that he had found her dependable.
Around midday on Sunday, March 16, 1997, Ayaka was struck on the head with a heavy iron hammer in a residential street in Suma Ward. The family court found that the attacker had at least a conditional intent to kill. She was taken to hospital with a severe brain injury.
Kota came home from baseball practice that afternoon to find a note on the front door saying that his sister had been hurt and taken to hospital. He went there with a neighbor. He visited every day, hoping she would recover. Ayaka died on March 23, 1997, a week after the attack.
About ten minutes after the attack on Ayaka, and roughly 150 meters away, a 9-year-old third-grade girl was stabbed with a knife. She survived; the family court recorded that her injuries needed about two weeks of treatment and found that the attack was an attempt to kill. She is not named here.
The two attacks were made with different weapons, and investigators did not at first treat the March street attacks and the later killing as one case. Prosecutors later learned that after the March attacks the boy had written an essay whose title compared life to a prison sentence; the chief prosecutor said in 2022 that he wished he had had more time to examine it.
Hyogo Prefectural Police set up a murder investigation headquarters at Suma Police Station. The girl who had been stabbed had seen her attacker's face. Door-to-door inquiries turned up a man in his late twenties who lived between the two attack sites and whose height and hairstyle matched the witness descriptions. In April 1997 police questioned him voluntarily, using their most experienced interrogator, and tested a bat he handed over. Nothing supported the suspicion, and he was released without arrest. Years later the chief prosecutor on the case told the Kobe Shimbun that police had come close to arresting the wrong man. That man had nothing to do with the crimes and is not identified here.
Jun Hase was 11 and in the sixth grade, the younger of two sons of Mamoru Hase, a radiologist born in Kobe in 1956. His father has described him as a gentle child. In 2026, asked what he remembered most, Mamoru Hase said it was not the family trips but ordinary daily life, and that simply being able to live normal days, with both anger and laughter in them, had been a great happiness. Jun knew the boy who killed him; the Irish Times, reporting the confession in 1997, called him an acquaintance.
Mamoru Hase's memoir of his son, Jun, published by Shinchosha in 1998, opens with the boy leaving home one day saying he was going to his grandfather's house. The sound of the door closing behind him was the last time his family saw him.
That day was Saturday, May 24, 1997. The family court found that the boy lured Jun to a secluded spot on a wooded hill above the neighborhood, a place local people called Tank Mountain, on a false pretext, and strangled him there. Over the following days, the court found, he mutilated the body, hid it at the site and then took Jun's head to the gate of a public junior high school in Suma Ward.
Jun's family reported him missing, and a public search began. Early on the morning of Tuesday, May 27, a school custodian found the head at the school's front gate. A note left with it called the police fools and boasted of enjoying seeing people die; one line announced, "Now the game begins." Jun's body was found the same day on the hill.
The discovery made national and international news. In the weeks that followed, parents and teachers walked children to and from school in groups, often with patrol cars alongside. Parks emptied, and families bought personal alarms that children could sound if a stranger approached. Reporters and television crews crowded the residential streets, so many that investigators complained they could not talk to residents.
In early June the Kobe Shimbun received a letter claiming responsibility. The newspaper has dated it to June 4, 1997. It was written in red, in stiff, ruler-straight characters, and signed with the full alias, 酒鬼薔薇聖斗. The Associated Press described it as a rambling letter of about 1,400 words. It threatened to kill three more people a week if the writer became upset, using the word "vegetables" for his targets, which police took as a contemptuous term for people. It mocked investigators for seeming bored and urged them to come after the writer with more anger and determination.
The letter also attacked the education system. One line, as translated by the Irish Times, read: "I am not forgetting revenge for the compulsory education that has produced me as an invisible existence." The phrase about an "invisible" or "transparent existence" (tomei na sonzai) was quoted endlessly in Japan that summer, and well-known commentators praised the letter's literary quality. Masashi Kawana, a Mainichi Shimbun reporter who has covered juvenile crime for more than twenty years, argued in a 2025 book that much of the letter echoed lines from manga and films of the time, and that commentators had projected onto an anonymous boy an inflated, almost superhuman image of their own making. People who worked with him in the reformatory, Kawana wrote, mostly saw him as an emotionally unstable child.
In the month before the arrest, witnesses reported seeing a man in his thirties or forties near the school shortly before the head was found, and media speculation focused on an adult. The arrest of a 14-year-old was, the AP reported, unexpected.
Quietly, the investigation headquarters had begun to look at a juvenile. In the spring of 1997, dead cats and pigeons had been found near the school gate and elsewhere in the area, and NHK reported after the arrest that killings of pigeons and other small animals had led police to the boy. According to investigators interviewed by the Kobe Shimbun in 2023, he was privately regarded as a suspect because of a record of cruelty to animals, and officers on house-to-house inquiries had been told not to stop him.
On June 1, 1997, two officers, a sergeant in his thirties and an older senior sergeant, saw the boy on his bicycle. The senior man encouraged his colleague to question him anyway, and they stopped him. For about half an hour the boy talked at length about the case, including the note left with Jun's head, mixing in lies. The sergeant noticed a stain that looked like blood on his shoe.
On the evening of Saturday, June 28, 1997, Hyogo Prefectural Police arrested the 14-year-old. The senior investigator announced at a nationally televised news conference that the boy had confessed after several hours of questioning to killing Jun Hase. Police then found a knife believed to have been used in the killing at the boy's home. The investigator declined to say how the boy had been identified.
Over the next day Japanese news organizations, apparently drawing on a confidential police briefing, reported that he had also confessed to the March attacks on Ayaka and the girl who was stabbed. In Kobe, a mother told NHK she was relieved: she had always worried whether her child would get to school and home safely.
That same night, under a duty-lawyer system the Hyogo Bar Association had introduced that year, a group of four lawyers led by Osamu Hashiba, then head of the bar association's criminal defense center, went to Suma Police Station. Hashiba later said that at first the lawyers doubted that a single boy could have committed all the crimes, but that reading the case records, including a drawing the boy had made, convinced them both of his involvement and of a deep psychological disturbance. Hashiba went on to support the boy's family, unpaid, for more than two decades.
The chief prosecutor in the case questioned the boy for nearly 30 days, more than 100 hours in all, the limit set by the detention rules for a suspect of his age. He told the Kobe Shimbun in 2022 that he had recorded the boy's statements unless they plainly contradicted the physical evidence, because the Juvenile Act puts rehabilitation first, and that he still could not say whether the boy had really understood his own feelings. He admitted that there was a risk, in long questioning, of leading a suspect's answers.
When the case was referred to the family court, prosecutors took the unusual step of holding a news conference. They said the starting point was the death of the boy's grandmother, after which he had become fascinated by death.
The family court did not accept everything the investigators produced. Its decision excluded the boy's statements to police about the May killing, because the officer who questioned him had falsely told him that handwriting analysis matched his writing to the letters when it had not. The court admitted his statements to prosecutors, who had clearly told him that he could stay silent and need not repeat anything he had said to police.
In 1997 Japan's Juvenile Act, which dated from 1948, did not allow anyone under 16 to be sent for criminal trial. A 14-year-old who killed could be dealt with only through the family court's protective measures, which aim at rehabilitation rather than punishment. Juvenile hearings were closed, and the families of victims could not attend or read the records.
The arrest set off an immediate debate. On July 1, 1997, three days after the arrest, the Chief Cabinet Secretary, Seiroku Kajiyama, told a news conference that the government should consider revising the Juvenile Act.
Article 61 of the Juvenile Act forbids the media from publishing a juvenile offender's name, face or anything else that would identify him. Within a day of the arrest, the boy's real name was circulating on the internet. On July 2, 1997, the weekly photo magazine Focus published his photograph in breach of the law. Some shops refused to sell the issue and others sold out, and the issue was later pulled from sale. Mainstream newspapers and broadcasters did not identify him.
A second controversy followed in early 1998, when the monthly magazine Bungei Shunju printed, in its March issue, statements the boy had given to prosecutors, describing his methods and state of mind. The Supreme Court's family affairs bureau protested, the Justice Minister ordered an inquiry into the leak, and a member of the House of Representatives, Tomio Sakagami, put written questions to the cabinet about it on February 18, 1998.
The hearing was conducted by Judge Yasuhiro Igaki of the Kobe Family Court. On October 17, 1997, the court ordered the boy committed to a medical juvenile training school, a reformatory with psychiatric care. Because of the case's social impact, the court released a summary of its decision, something not normally done in juvenile cases.
The court found as facts the February assault on the two 12-year-olds, the fatal attack on Ayaka, the attempt to kill the girl who was stabbed, the killing of Jun and the mutilation and abandonment of his body.
It relied on a joint report by two psychiatrists, based on medical examinations, psychological tests and about a dozen interviews. As summarized by the court, the report found that:
he was not psychotic, either at the time of the crimes or when examined; his consciousness was clear and his judgment normal for his age;
he had a persistent, entrenched sexual sadism, formed from undifferentiated sexual impulses fused with aggression, which the experts saw as a major factor in the crimes;
he showed depersonalization and a tendency to dissociation, but the crimes were not committed in a dissociated state or by a split personality;
an unusually strong capacity for vivid visual imagery played a part;
low self-worth and limited empathy, rationalized as a denial of other people's worth, had made the crimes easier for him.
The court treated the crimes as the extreme end of a long, escalating series of antisocial acts. It found that, despite these personality deviations, he had nothing equivalent to the diminished responsibility recognized in adult criminal law.
The court did not adopt the prosecution's account of a fascination with death sparked by his grandmother's death. Its reasons for choosing a medical reformatory pointed instead to his long history of cruelty and isolation and to his relationship with his mother and his upbringing. It saw early signs of conscience: although he still justified his acts outwardly, he had nightmares and a sense that the victims' spirits had entered him. Because he was young, the court thought ordinary guilt, conscience and sexual development might still grow.
It set out a detailed treatment plan. He should be held in a calm, structured setting, begin with one-to-one relationships before gradually joining groups, receive training in social skills, and see a psychiatrist at least weekly. The court warned of a risk of suicide as his conscience developed, and of the possibility of serious mental illness. It recommended that he stay until rehabilitation was truly achieved, not for a fixed term, and said that outward good behavior alone would not prove change.
The defense team was led by the lawyer Yoshikuni Noguchi. He later said the court had stressed the boy's abnormal character too heavily and risked misleading the public, while admitting that the defense had not analyzed the motive for each offense.
On October 20, 1997, the boy was moved from the juvenile classification home in Kobe to a medical reformatory in Tokyo: the Kanto Medical Reformatory in Fuchu. Over the next six and a half years he received psychiatric treatment, counseling, vocational training and social skills training. The Japan Times Weekly reported in 2004 that he had spent time at two reformatories.
The journalist Atsuko Kusanagi's 2004 book on his treatment, published by Bungei Shunju, describes a confidential program built around him and called the "Boy A Rehabilitation Project," and asks whether his sadism had really been overcome. Judge Igaki visited him at the reformatory every year, encouraged him to read what the victims' families had written, and tried to build trust with the victims' side. In 2002, at a review of his progress, the boy told his father that he wanted to make amends and would never forget what he had done.
According to Masashi Kawana, he was originally expected to leave in the spring of 2003, after five and a half years. In the end, on March 10, 2004, the Kanto Regional Parole Board, having interviewed him, granted him provisional release from the Kanto Medical Reformatory. He was 21 and had been held for six years and five months.
For the first time in a Japanese juvenile case, the Justice Ministry announced the release publicly, citing the case's social impact, and the parole board notified the victims' families. Officials said he regretted his crimes and wanted to spend his life making amends. Mamoru Hase held his first news conference that day. Asked about the possibility of the former Boy A one day appearing in paid media interviews, he said the family absolutely did not want that.
The Tokyo probation office gave him unusually close support, starting with three probation officers. At the first rehabilitation hostel he stayed in, his identity was quickly discovered and he had to move. After two months he went to live with foster parents who acted as his guarantors. His supervision ended on December 31, 2004, and he was formally discharged on January 1, 2005. Justice Ministry officials said at the end of 2004 that he was healthy, employed and leading "a stable and quiet life," and that volunteers would form a support team; the families would receive reports on his condition.
According to his own memoir, as summarized by Kawana, he worked in a series of manual jobs after his discharge. About six months later he left his first job and cut contact with his supporters, though they had arranged to keep helping him. In the memoir he wrote that he had always been managed by someone: by his parents, school and community before his arrest, by the state after it, and by his support team after his release.
After his release the former Boy A sent the Hase and Yamashita families a letter of apology every year, timed to arrive before the anniversaries. The letters were passed on by Osamu Hashiba, who had become the lawyer for the boy's parents and who also handled compensation payments to the families. The former Boy A reportedly sent 10,000 yen a month from his earnings.
Mamoru Hase read the letters closely and tried to read them generously. In his annual statements he wrote that he could see change and growth in them. Hashiba said that the letters grew from short notes into longer ones, especially in 2013 and 2014. The letter of 2015 ran to 37 word-processed pages. Hase felt that it explained the cause of the crime in the former Boy A's own words, almost like a secret shared only with the family, and he and his wife thought it might be a natural point to stop analyzing the letters.
Kyoko Yamashita, Ayaka's mother, met the boy's parents several times at Hashiba's office. She pressed them hard, telling them that if she were a parent she would go to see her child by any means. She told Hashiba that one letter a year was not enough if the remorse was real. In 2014 and 2015, as the letters became longer, she said she might be willing to meet him. Hashiba believed that she remained doubtful but felt a strong duty to hear from him why her daughter had been killed.
On June 11, 2015, about a month after the long letter, the Tokyo publisher Ohta Publishing released Zekka (絶歌), subtitled "The Kobe Serial Child Killings," a 294-page memoir by "Former Boy A." The families had not been told. The first printing was 100,000 copies, and a further 50,000 were ordered within a week. The book went straight to number one on the weekly bestseller lists of the distributors Tohan and Nippan.
In the book, the Japan Times reported, he wrote of his reaction to one of the killings in admiring terms, alongside passages of regret. KTV reported that it described the experience he said had formed his sadism, an account that had also appeared in the 2015 letter to the Hase family.
On June 12, 2015, Mamoru Hase protested to Ohta Publishing and demanded that the book be recalled at once. He has said he has not read it. He suspected that the letter he had trusted had been condensed from the book, and he later said the publication made him feel that his son had been killed a second time. Hashiba believed that Kyoko Yamashita, too, came to feel that the letters she had trusted were drafts for the book, and that her disappointment was deep. She died of illness in 2017, at 61.
Ohta Publishing acknowledged a "massive" public backlash. In a statement of about 1,800 characters signed by its president, Satoshi Oka, and posted on June 17, 2015, it said the book was neither a self-justification nor an attempt to stir interest in the crimes, that the author had been an ordinary boy before the killings, and that exposing an offender's thinking had great social significance for understanding juvenile crime. The statement did not respond to the families' criticism.
Bookstores split. One Tokyo chain refused to stock the book in any of its 38 stores and turned down customer orders out of consideration for the families; a Kobe-based chain removed it from all 33 of its stores on June 12. Others sold it normally or took orders only. Critics objected to the anonymous authorship, to the lack of any warning to the families and to the unknown fate of the royalties. By late July the Japan Times reported growing calls for Japan to adopt laws like the American "Son of Sam" statutes, which keep offenders from profiting from accounts of their crimes. About three months after the book appeared, a policy body of the governing Liberal Democratic Party proposed lowering the upper age limit of the Juvenile Act from 20 to under 18, opening another round of debate on the law.
In March 2016 the former Boy A wrote to Hashiba offering to send 10 million yen of the royalties to the victims' families. The letter was signed with a name that matched neither of his parents' surnames and shared no characters with his original name, which Hashiba took as a sign that he had changed his name completely. That name is not given here. The sources consulted do not say what became of the offer.
The memoir year also brought a dispute over the 1997 decision itself. In early April 2015, the May issue of Bungei Shunju printed the full text of the decision, including details of the boy's upbringing and the main parts of the psychiatric report that the public summary had left out. Judge Igaki, by then retired and practicing as a lawyer, had given it to a Kyodo News senior writer. The Kobe Family Court protested that the disclosure broke a judge's duty of confidentiality and damaged trust in closed juvenile hearings. Igaki argued that the omitted details were needed to understand the case. In July 2015, after Zekka appeared, he wrote about the case again in the same magazine. The victims' families objected, and the Osaka Bar Association suspended him from practice for three months. Igaki, who later argued for more openness in juvenile justice, died on February 26, 2022, aged 82.
In 2015, around the time of the memoir, the former Boy A opened a website titled "The Unbearable Transparency of Being," echoing the "invisible existence" of his 1997 letter. The weekly magazine Shukan Gendai, describing it in September 2015, reported that the site promoted Zekka, invited readers to send feedback by email, and showed his own illustrations and photo collages, many featuring snails, along with an open letter to Issei Sagawa, a Japanese man who killed a woman in Paris in 1981. The magazine also reported, without independent confirmation, that he had written to weekly magazines and newspapers to publicize the site. The site stopped being updated on January 12, 2016, and has since closed. The comedian Hikari Ota dismissed its artwork as entirely ordinary for someone who thought himself special, a judgment Kawana later quoted with approval.
In its issue dated February 25, 2016, the weekly Shukan Bunshun said its reporters had searched for him from shortly after the memoir's publication, found him in late September 2015 and watched him for about four months, and that two reporters approached him on January 26, 2016. He denied being the person they were looking for. The magazine's methods, including printing photographs with his eyes masked, were widely debated. No photograph is used or described here.
The Kobe killings are one of several juvenile cases of the late 1990s that are credited with driving the first major revision of the Juvenile Act since 1948. Writing in Keio University's Mita Hyoron in 2022, Hiroko Goto named the Kobe case as one of the triggers: it exposed the fact that no one under 16 could be tried in a criminal court, however serious the crime. Nippon.com lists it alongside other cases from 1988 to 2000.
The Law for Partial Amendment to the Juvenile Law (Law No. 142 of 2000) was passed on November 28, 2000, and took effect on April 1, 2001. It lowered from 16 to 14 the age at which a family court can send a juvenile to prosecutors for criminal trial. It made referral the presumption for juveniles aged 16 or older who intentionally cause a death. It also gave victims and bereaved families new rights: to state their views, to learn the outcome, and to read and copy parts of the hearing records.
The new law did not reach back to the Kobe case. The window for victims to see the records, three years after a case ended, had already closed by the time the law took effect, and Mamoru Hase never saw the records. Later amendments, which the bereaved families' advocacy helped shape, lowered the minimum age for reformatory placement to about 12 in 2007, let victims' families attend hearings in serious cases from 2008, and in April 2022 created a separate category of "specified juveniles" for 18- and 19-year-olds. Hase, who supports the basic spirit of the Juvenile Act, called the 2022 arrangement a complete double standard.
The case left other marks. In 1998 Hyogo Prefecture launched "Try-yaru Week," a week of workplace experience for second-year junior high school students, partly as a rethinking of moral education. In 2000, a 17-year-old who hijacked a bus in Kyushu and killed a passenger said he had been influenced by the Kobe case.
On October 20, 2022, the Kobe Shimbun revealed that the Kobe Family Court had destroyed every record of the case: the full decision, the investigation files sent by police and prosecutors (four cardboard boxes stacked more than two meters high), the psychiatric report and the reports on the boy's upbringing. Supreme Court rules already allowed records of nationally significant cases to be kept permanently. A Supreme Court investigation later dated the destruction to February 28, 2011. A former chief clerk said he had approved it, and staff had reasoned that the Kobe court had never permanently preserved a juvenile file and that juvenile cases are closed to the public.
The court first said only that the handling had not been appropriate by current standards. As other courts were found to have destroyed records of major cases, criticism grew, and on November 22, 2022, the Supreme Court's secretary-general, Shinya Onodera, apologized in the House of Councillors. On May 25, 2023, the Supreme Court published its investigation report and apologized for losing records that should have been handed down to future generations. New rules took effect on January 30, 2024, describing historically significant records as shared national property.
Mamoru Hase, who had hoped to read the account of the boy's upbringing and the psychiatric report, called the destruction something "a normal organization would not do." After a senior Supreme Court official explained it to him on June 2, 2023, he said he saw the case not just as a juvenile record but as history. The Kobe Shimbun reported that the Supreme Court did not substantially change its criteria for preserving juvenile records.
The Hase and Yamashita families have spoken publicly for nearly three decades. Mamoru Hase has issued a written statement to the media every year since 1998. He has campaigned for victims' rights, and in 2023 he welcomed a new Hyogo Prefecture ordinance on support for crime victims, which he called the first in Japan to affirm victims' rights.
Kyoko Yamashita wrote about her daughter and about her own illness, including in Ayaka ga oshiete kureta shiawase ("The Happiness Ayaka Taught Me," Poplar, 2003), and she and her husband gave talks about the value of life. In 2017 she told the Kobe Shimbun she regretted having put too much pressure on Kota to live for Ayaka's sake. Kota said he had first wanted to do to the attacker what had been done to his sister, but over time had come to feel nothing toward him, and that the best way to honor Ayaka and his parents was to live a happy life.
On the 25th anniversary, in March 2022, Kenji Yamashita wrote that he had walked "a thorny path" for 25 years, that Ayaka's presence would never fade, and that he had kept going after her death largely because of his wife. He said no letter had come from the former Boy A since 2018, asked whether he felt any remorse, and said he would keep seeking compensation and an apology. He did not want the burden handed down to his son's generation.
After Zekka, the families refused to accept further letters. By the Hase family's account the letters continued to arrive until 2017; none has come since. On the 25th anniversary of Jun's death, in May 2022, Mamoru Hase addressed the former Boy A directly through his lawyer: "Why did the life of my second son have to be taken? You are obliged to answer the question." Hashiba, asked that year whether the rehabilitation had succeeded, said he could not believe it had, and that the former Boy A had come close to a breakthrough and then let it go.
As of the latest reports, the former Boy A's whereabouts are not publicly known. When the Kobe Shimbun looked for him in November 2021, residents of a Tokyo neighborhood where he had reportedly lived did not know where he was, and the newspaper reported that even his parents did not know. Kawana wrote in May 2025 that he was 42 and that, whatever doubts surround his rehabilitation, he was not known to have reoffended.
In May 2026, before the 29th anniversary of his son's death, Mamoru Hase, 70, told Jiji Press that there had been no recent contact from the man and no letters since 2017. He repeated that the family wanted to know why Jun had been killed, in the man's own words rather than through expert opinion. He said the memoir's publication without consulting the families made a sincere apology hard to believe in. He asked the public not to spread rumors or speculation about victims and their families online, and said there would be no closure for him until he died. No later development was found when this was checked in October 2026.
Established by the family court (not a criminal conviction): the February 10 assault, the fatal attack on Ayaka Yamashita, the attempt to kill the girl who was stabbed, and the killing of Jun Hase. The boy confessed to police and prosecutors, the court relied on his statements to prosecutors, and he later described the killings in his own memoir. The Kobe Shimbun noted in 2022 that no doubt had arisen about his responsibility. His own defense lawyers said they had doubted at first that one boy could have done everything, and changed their view after reading the case records.
Excluded by the court: his statements to police about the May killing, because an officer falsely told him his handwriting matched the letters.
Contested: the motive. Prosecutors argued that his grandmother's death had sparked a fascination with death; the family court did not accept that and pointed to his personality, upbringing and relationship with his mother. The chief prosecutor himself said in 2022 that he still doubted his own explanation, that the boy's inner motives could not really be verified, and that key questions remained unanswered: why the body was mutilated, why it was left at a school gate, and why the attacks stopped after May. The defense leader felt the court had overstated the boy's abnormality.
Unconfirmed: a weekly magazine's 2015 report that he had written to magazines and newspapers to publicize his website; reports that he has changed his name (inferred by Hashiba from the signature on a 2016 letter; no name is given here). Whether the royalties offer of 2016 was accepted or paid is not reported in the sources consulted.
Errors in early reports: some 1997 wire reports said Ayaka died of stab wounds; the family court found she was struck with a hammer, and it was the second girl who was stabbed. Some later summaries give Jun's school year incorrectly or place his disappearance on May 26; the court's finding is that he was killed on May 24.
1982: the boy later known as Boy A is born.
January 1995: the Great Hanshin earthquake devastates Kobe.
Spring 1997: dead cats and pigeons are found near a junior high school in Suma Ward.
February 10, 1997: two 12-year-old girls are struck with a hammer; one is injured.
March 16, 1997: Ayaka Yamashita, 10, is struck on the head with a hammer; about ten minutes later a 9-year-old girl is stabbed and survives.
March 23, 1997: Ayaka dies.
April 1997: police question an adult man who lived near the scenes and release him; he had no involvement.
May 24, 1997: Jun Hase, 11, leaves home and is killed on a hill in Suma Ward.
May 27, 1997: part of Jun's body is found at the gate of a public junior high school with a taunting note; his body is found on the hill.
June 1, 1997: two officers stop and question the boy on his bicycle.
About June 4, 1997: the Kobe Shimbun receives the letter signed "Seito Sakakibara."
June 28, 1997: the 14-year-old is arrested and confesses.
July 1, 1997: Chief Cabinet Secretary Seiroku Kajiyama says the Juvenile Act should be reviewed.
July 2, 1997: Focus magazine publishes the boy's photograph in breach of the Juvenile Act.
October 17, 1997: the Kobe Family Court commits him to a medical reformatory and releases a summary of its decision.
October 20, 1997: he is moved to the Kanto Medical Reformatory in Fuchu, Tokyo.
February 1998: Bungei Shunju prints his statements to prosecutors; a Diet member questions the cabinet on February 18.
1998: Mamoru Hase publishes Jun; Hyogo Prefecture starts "Try-yaru Week."
November 28, 2000: the Diet passes the Juvenile Act amendment.
April 1, 2001: the amendment takes effect; the age for criminal punishment falls from 16 to 14.
March 10, 2004: provisional release; the Justice Ministry announces it publicly, a first.
December 31, 2004: supervision ends.
January 1, 2005: formal discharge from the reformatory.
2005 onward: annual letters of apology to both families.
February 28, 2011: the Kobe Family Court destroys the case records (date established in 2023).
April 2015: Bungei Shunju prints the full 1997 decision, supplied by retired Judge Igaki.
June 11, 2015: Zekka is published by Ohta Publishing under "Former Boy A."
June 12, 2015: Mamoru Hase demands that the book be recalled.
September 2015: his website is reported in the press.
January 12, 2016: the website's last update.
March 2016: he offers 10 million yen in royalties to the families through a lawyer.
2017: Kyoko Yamashita dies, aged 61; last letters from the former Boy A.
February 26, 2022: Judge Igaki dies, aged 82.
April 1, 2022: the "specified juvenile" amendment takes effect.
October 20, 2022: the destruction of the case records is reported.
November 22, 2022: the Supreme Court apologizes in the Diet.
May 25, 2023: the Supreme Court publishes its investigation report and apologizes.
January 30, 2024: new rules on preserving court records take effect.
May 2025: Kawana's book reports that he is not known to have reoffended.
May 2026: on the 29th anniversary, Mamoru Hase says there has been no contact; whereabouts not publicly known.