Nikaido Katsuo, a.k.a. "Fist King," is the most powerful and undefeated delinquent in Japan. However, no one knows that behind the stories of his legendary battles, there is a girl behind the scenes... Her name is Tabara Nikaido. She is the fighter who took her brother's name and fought in secret, and defeated all the strong men in her way....... A slightly naughty story about a legendary fighter who happens to be a "tsuyokawa" JK!