National Treasure Onimaru Kunitsuna.High School first year and Sumo wrestler Hinomaru Ushio saves Chizuko Hori from a molester on a train but is himself arrested for only wearing a Mawashi. Hinomaru rushes to school and overhears fellow Sumo student Shinya Ozeki practicing. He offers to spar with him, revealing a heavily scarred yet extremely muscular body. Hinomaru easily wins despite his short stature. Shinya is overjoyed someone wants to join Sumo Club but reveals the other members are all delinquents who use the dojo as their headquarters. Hinomaru confronts them and learns that he accidentally came to the wrong school, Odachi High instead of Ishigami High...