Tetsuya Nakanishi is a trapeze artist working in a circus troupe in Hawaii. He started boxing after being discovered by former boxer Jimmy Smith, and won many fights and overcame many crises with his special punch, the "cross-shaped triple strike," which he adapted from his father, a famous Zero pilot. After winning the championship in New York, Tetsuya returned to Japan, his parents' home country, with Coach Smith, his daughter Marie, and his best friend Sanpei to make it in the Japanese boxing world.

During the Pacific War, there was a squad of young men who combined modern science with mastery of the ninjutsu of the Koga and Iga schools. The name of this ninja-soldier unit was "Gekkou"!