ウルトラレッド

Sen Sumeragi is thirteen and fights with a style his absent father taught him, one built on taking a body apart the way you would take apart a puppet. He moves in with his grandfather at the Akiba dojo and finds it emptying out, its students drawn away by Ryu'en, the full-contact gym down the road. Sen walks into Ryu'en, challenges the man who runs it and puts Hideto Katakura in hospital, which only brings out fighters made to answer him, and Sen starts finding out where his own limit sits.