On July 25, 1998, at a summer festival in the Sonobe district of Wakayama, residents ate curry prepared communally in a large pot. Sixty-seven people were poisoned. Four died: Takatoshi Taninaka, sixty-four; Takaaki Tanaka, fifty-three; Miyuki Torii, sixteen; and Hirotaka Hayashi, ten.
Masumi Hayashi, born July 22, 1961, lived in the neighbourhood and had helped at the festival. She and her husband had a history of insurance fraud involving arsenic, he had been made ill repeatedly and policies claimed, and arsenic traces were found at her house and, the prosecution said, on her clothing.
There was no confession, no witness to her putting anything in the pot, and no direct evidence of the act. The case rested on her access to the pot during an unattended period, on the arsenic found at her home being of a composition said to match that in the curry, and on her history. The defence disputed the arsenic comparison, which relied on trace-element analysis by synchrotron radiation. A technique whose application here has been questioned by Japanese scientists since.
She was convicted and sentenced to death on December 10, 2002. The Osaka High Court upheld it in 2005 and the Supreme Court in 2009. She has consistently denied the poisoning and has sought a retrial repeatedly; a request was rejected in 2017 and further applications have followed.
She remains on death row. The entry records the conviction and, with equal weight, that it rests entirely on circumstantial evidence and contested science, because a substantial body of Japanese legal and scientific opinion regards the case as unsafe.