On April 15, Nobuyoshi Sasaki, 49, and Michihiro Uehara, 50, allegedly assaulted Toshihisa Kato, 50, at the residence of a mutual acquaintance in the town of Kaisei.
Kato, a plasterer, was later transported to a hospital. However, he was later confirmed dead as a result of shock due to loss of blood, police said.

The acquaintance was out when the incident took place. When he returned at around 8:30 p.m., Kato was lying on the floor and bleeding. By the time of the arrival of the authorities, Sasaki and Uehara had fled.
At around 10:00 a.m. on April 26, Sasaki and Uehara surrendered to police. They were later accused of manslaughter. Uehara admits to the allegations. However, Sasaki said that “[the facts] are different [from the allegations].