Hiroyuki Tsuchida

Hiroyuki Tsuchida (土田博行) (b. 1981) is a Japanese man convicted of killing his mother and the family's pet cat in 2003 in Yonezawa, Yamagata Prefecture. Tsuchida, an otaku and once a recluse was a fan of the Japanese anime series Neon Genesis Evangelion, which he said inspired him to commit murder based on the phrase that "The ultimate conclusion of human evolution is ruin." On June 14, 2003, he beat his mother to death with a baseball bat, and said that killing a close relative first would make him avoid hesitation when it came to killing others.

After killing his mother, he escaped and wandered through Gunma Prefecture, Niigata Prefecture and the Tokyo Metropolitan Area, he traveled to Nagano Prefecture where he tried to commit suicide after trying to kill other people. After failing to commit suicide, he was arrested by local police and charged with the murder of his mother.

Two weeks before the crime, he had sent an e-mail to a friend telling him: "I'll kill you". In February 2004, he was convicted of the murder of his mother and sentenced to fourteen years in prison.