Hideo Shimazu, along with Kyoko Minazuki, is asked by the school president of Justice High to scout for potential students around Aoharu. After starting to question their employer's intentions, both of them are brainwashed into becoming unquestioning servants of Justice High. They are eventually brought to their senses by the student of Taiyo High and decide to confront Justice High. Hideo's ending sees him inspired by the bravery of the students as he confides in Kyoko. He meekly attempts to ask her to marry him.
A year after the events of the first game, both Hideo and Kyoko have reconciled with Raizo Imawano and resumed working for Justice High. After Raizo is attacked and left hospitalized, the two set out to investigate who was behind the assault. They eventually team up with Hayato Nekketsu, P.E. teacher from Taiyo High, and are confronted by the imposter Batsu who later kidnaps Kyoko. After Kyoko is rescued, the trio takes on Kurow and then finally a possessed Hyo Imawano. Two weeks after the incident, Hideo is recovering in hospital with both Kyoko and Hideo visiting. Hayato remarks how jealous he is of Hideo having Kyoko look after him and congratulates them on their eventual engagement.
Hideo is a stereotypical gentlemanly teacher who leads a strict life of no drinking or smoking. He is a master of Shimazu-style karate of which he is a ninth dan. He ran away from home when he was younger due to his family arguing over who would be the successor of the family estate after his father passed away. His speech and social skills are considered to need improving.