In a city in the Kyushu region, a vicious bus hijacking incident occurred. The only survivors were driver Sakai and a pair of siblings, middle school student Naoki and elementary school student Shuo. Witnessing the other passengers being shot to death in front of his eyes, and his own fate, tormented by this nightmare experience, he left the city. Two years later, Sawai returned to his hometown. He visited the home of the surviving siblings, and when he learned that they no longer went to school because of the events of the year, Sawai and the siblings, as well as their distant relative Akihiko, started living together .
At this time, serial killings began to occur around, and the police began to suspect Sawai. After a woman related to Sakai was also killed, Sakai was arrested, but he was released immediately because of an alibi. Sakai drives a bus and leaves the city with the siblings and Akihiko despite the police's obstruction
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