One day, Jojima receives a request to kill an old friend, Yamauchi, a young leader of the Oyama clan. His target is Li, the head of the Beijing mafia who killed the clan leader Oyama. Jojima begins to investigate and discovers the existence of an underworld war of interests.

Kaori Yumiko is a high school girl with large boobs and a track athlete. One day, she is hit by a car and seriously injured, but her life is saved by surgery performed by Dr. Osuga. However, Yumiko's breasts have been transformed into a peculiar condition where they become huge when she gets excited! Using the power of her gigantic breasts, she wins the track and field championship. She quickly becomes a beautiful busty idol star, but then another super busty idol appears who persistently harasses Yumiko. In fact, this idol is a member of the evil busty army "Ura Mespai"! And Dr. Osuga is none other than the head of the Japanese branch of "Mespai," a secret female organization fighting for world peace. Now the final battle between Ura Mespai and Mespai has begun!