Japanese people were attacked and killed one after another by the Moromoro group based on Rupat Island, a small island in the South Sea. Still, one man landed on Rupat Island. The man was also attacked by the Moromoro group, but was saved by a boy named Harimao. Why are those who approach Rupat Island targeted? The curtain begins on a fierce battle between Harimao, a young boy who has been taught the Koga style of martial arts by Captain Koga since he was 5 years old, and the Moromoro Gang, an evil group that disrupts the peace of the world. And the fight involves the people around her, including the nurse's Chihuahua...