Ultimo and Vice are Karakuri Doji, the mechanical embodiment of pure good and pure evil, devoid of human emotions that can cloud one's judgment. Their purpose: to battle to the death to prove once and for all whether good or evil is the most powerful force in the universe.

Locked in a battle that spans the ages, Vice and Ultimo, along with their human proxies, duel in the wartime arena of Tokyo, 1947. Among the bombs and destruction, dôji masters on both sides seek to convince their counterparts to switch teams—good to evil and vice versa. Which force holds ultimate sway over human history?