Sumida was born in 1948 and lived in Amagasaki, in Hyogo prefecture. Over years she installed herself in other people's households, through relationships, through debt, through her own relatives, and established control over them, isolating members from one another, dictating who ate and who was beaten, and taking over the family finances. She used other members of the household to carry out the violence, which is the defining feature of the case.
Between 2003 and 2011 six people died: Hisayoshi Sumida, fifty-one; Kazuko Oe, sixty-six; Jiro Hashimoto, fifty-four; Mitsue Ando, seventy-one; Mariko Nakashima, twenty-nine; and Takashi Ando. They died of beatings, starvation and dehydration while confined in flats. Insurance and pension money was collected in each case. Several other people who survived the confinement gave evidence.
She was arrested in 2011. On December 12, 2012, before her trial, she hanged herself in her cell at the Hyogo detention centre.
Because she died before trial, nothing against her was tested and there is no judgment. Several of the people she had directed were prosecuted and convicted, and their trials are the record of what happened; the Japanese press called her the piranha grandmother. The count of six is what the investigation attributed to her.
The case is discussed in Japan alongside the Kitakyushu case of Futoshi Matsunaga and Junko Ogata in this archive: both involve a person who took over a family and had its members kill one another, and in both the physical evidence was almost entirely destroyed or absent.