During questioning, Hirose said that the murder came about after the pair got into a money-related dispute inside his vehicle while it was parked on a farming road on the night of November 20. "Since she threatened to spread information [about me on the internet], I killed her," the suspect told police.
According to police, the suspect allegedly blocked the victim's mouth and nose in fatally suffocating her.
Police first arrested Hirose on January 31 after he admitted to burying her body in a field near the coast - about 13 kilometers from his residence in Kamisu - during questioning. The results of a DNA analysis confirmed that the body was that of Kikuchi.