Aya, Youji, Ken, and Omi are the four young men who comprise Weiss Kreuz (WK), an assassin group that eliminates certain menaces to society. Each member has his own trademark fighting style. Aya is adept at fighting with a katana, Youji has mastered the art of strangulation via strings, Ken is lethal with his metal claws, while Omi specializes in a

Mars is discovered on a forming volcano island, Heisei; a man with no memory. In reality, Mars is from outer space, and is supposed to gather information to decide whether Earth should be destroyed or not. Along with the giant robot Gaia, and his mysterious images of a woman urging him not to destroy the world, Mars decides to fight for Earth rathe