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.

In a trip to the future to try to avert the errors of the past, Yamato, Ultimo’s master, is shocked to discover that his high school crush Sayama is in fact a close relation of the evil puppet master Dunstan. Then, when he joins with Ultimo to create a powerful new weapon called God Ultimo Frontal Till Dawn, Yamato finds he must reconcile his feelings for his classmate Rune—an agent of evil—and his crush on Sayama!