The story focuses on Kenichi Shirahama, an average 15-year-old high school student who has been picked on his whole life. However, after a month into his freshman year, he meets and befriends the mysterious transfer student, Miu Fūrinji. Driven by his desire to become stronger and to protect those around him, he follows her to Ryōzanpaku, a dojo where those who are truly strong and have mastered of their art gather. After learning basics from Miu, Kenichi is able to beat a high ranking member of the school's karate club, and becomes a target for all the delinquents in the school. Subsequently, Kenichi's daily routine is divided between hellish training under the six masters of Ryōzanpaku, and his fights against the members of Ragnarok, a gang that views him as either a possible ally or an impending threat to their plans. After defeating Ragnarok, he faces a new enemy called YOMI, a group of disciples who are each personally trained by a master of an even bigger organization rivaling Ryōzanpaku, Yami. Along with former members of Ragnarok who joins the Shinpaku Alliance, a group created by Kenichi's schoolmate Haruo Niijima, Kenichi now fights Yami to prove his ideals and protect those in need.