Editing Tomohiro Katō

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Tomohiro Katō (加藤智大, Katō Tomohiro?) (born September 28, 1982) grew up in a suburban home in Aomori, Honshu. His father was a top manager in a financial institution. Katō's grades were considered to be exceptional in elementary school and he was a top track athlete. He entered Tsukuda Junior High School and became president of the tennis club in middle school. He started to act violently at home after enrolling at Aomori Prefectural Aomori High School, an elite high school.

Katō was unpopular with his classmates and his class academic ranking fell to 300 (of 360 students). He failed entrance examinations for the prestigious Hokkaido University, eventually training as an auto mechanic at Nakanihon Automotive College. He was hired as a temporary worker at an auto parts factory in central Shizuoka Prefecture, though he was recently told that his job was going to be cut at the end of June.

Katō reportedly did not get along well with his parents, and seldom returned home. An interview with Katō's brother revealed that his parents had put immense pressure on them to perform, and to excel in their studies, ordering that their homework be redone to standards in order to impress teachers in school and recalling one incident where Katō was made to eat scraps of food from the floor.

Another neighbour described Katō being punished by his parents, who made him stand outside for hours in deep cold during winter. Previous online postings before his announcement of the attack contained sharp criticisms towards his own upbringing. Deeply in debt and believing that his family had given up on him, Katō unsuccessfully attempted suicide in 2006 by ramming his car into a wall