Kenichi Shirahama is a hapless, frail and friendless teenager, albeit one with a kind heart. Plagued by bullies, he signs up for his school's karate club, only to find its ranks filled with bullies as well. Things take a turn for the better though, when he encounters a beautiful transfer student named Miu Furinji. Miu is likewise friendless and wants to strike up a friendship, but when Kenichi sees her effortlessly trounces a group of thugs attacking an old man, he realizes that she is also a martial artist of amazing ability. She offers some martial advice that allows Kenichi to overcome a bully who targets him at the karate club, but this unfortunately incites the interest of the far more dangerous karate master.
Seeing how desperate he is, Miu guides Kenichi to her home, the Ryozanpaku dojo where some of the world's greatest martial artists have gathered.