Gaku Yashiro (八代 学, Yashiro Gaku), is the main antagonist of Erased. He is Satoru Fujinuma's homeroom teacher in primary five and a serial killer who primarily targets children. After Satoru's attempt at stopping his actions, he decided to drown Satoru in a frozen river, which resulted in Satoru's 15-year coma. In the 2006 timeline, he is going by the name Manabu Nishizono (西園 学, Nishizono Manabu), which is rather an obvious identity for Japanese speakers (Manabu and Gaku share the same Kanji).