In one of those nights that Sategawa takes a walk in the park, he makes the knowledge of Kensuke. That night when the first is invited to the home of the latter, he meets Kensuke's brother Oshiba known as the Bear killer because he beats gangsters in the streets. The TV series starts time after that night; Sategawa and Kensuke go to school together and Oshiba appears just to tell them that he will start teaching in the same school.