Kiba Yuuji is a ninja assasin, the only man in Japan who holds a murder license. and answers only to the Prime Minister of Japan, Itagaki Shigemasa. By using the Kiba ninja technique of muscles control, Yuuji is able to form his body into that of a woman, and is able to stay by the Prime Ministers side as his alter ego, Kiba Yuuko. Along with his mentor Kiba Sandayuu, Yuuji protects the Prime Minister as well as carries out any assassinations requested by the Prime Minister to protect both Japan and the world.