Un giovane viene aggredito per caso per strada. Decide allora di iscriversi in una palestra di karate guidata da un maestro tanto carismatico quanto misterioso per imparare a difendersi.

Per effettuare una speculazione edilizia un capomafia vorrebbe impadronirsi di un terreno sul quale sorge una scuola di karatè. Ma la giovanissima proprietaria, già esperta in quell'arte marziale, un poliziotto di colore e un ragazzo riescono a sconvolgere i piani dei banditi.

In Okinawa, Ayaka Kurenai was born in the world’s greatest legendary Karate family. When she was a child, her family was attacked by a mysterious gang that seeks legendary black belt. Her father Soujiro Kurenai was killed and her younger sister was taken in front of her. Time has passed. In Yokohama, she was spending her life as a normal high school girl, hiding her real name and her status as a heir of the legendary Karate family. However, one incident brought her a fateful encounter with her sister who was separated in their childhood. But, her sister was raised as a heartless killing machine by the mysterious gang who took her. .