NINKU is the most powerful method in martial arts, combining karate and ninja techniques. During a tragic war, a small NINKU team called “Ninkutai” defeated many opponent troops, but suddenly they stopped fighting and every member of Ninkutai disappeared unexpectedly. Three years after the end of the war, people have escaped from the terror of the war, but people are now suffering under the tyranny of a new government.
Fusuke, a member of Ninkutai, has been looking for his long-lost mother. On the way his search, Fusuke runs into other members of Ninkutai, and their journey begins. Sometimes they help people, and sometimes they fight against enemies who try to kill them. When Fusuke finds out the reason why his mother was abducted, a hidden conspiracy is revealed.