The story focuses on Kenichi Shirahama, an average 16-year-old high school student who has been picked on his whole life. However, on the first day of class, 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 their arts gather (Ryōzanpaku comes from the Chinese story of Heroes of the Water Margin who train together at Liangshan 梁山). 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. Kenichi's reason for training is to fulfill the promise he made to protect Miu. 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. He realized that he wanted to be the strongest in order to protect everyone without killing anyone. Along with former members of Ragnarok who joined 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.