The fate of Kenichi Shirahama, a friendless and defenseless schoolboy, changes dramatically when he meets Miu Furinji and begins training at the Ryozanpaku dojo. Pushed away by his classmates and called \"Weak Legs,\" Kenichi gains confidence and skill under the guidance of six martial arts masters. Every day becomes a test and a step towards overcoming his fears. As Kenichi pushes himself and his weaknesses, he faces unprecedented challenges, including a confrontation with the Ragnarok gang, who see him as a threat to their influence.