More than a thousand years ago, ninjas belonging to the Soukai Syndicate committed a forbidden form of hara-kiri, and stored their souls in the ancient Kinkaku Temple. Now, in the dystopia metropolis of Neo-Saitama, these sinister souls have been resurrected, and wreak havoc across Japan. Average salaryman Kenji Fukijidos wife and children are killed in ninja crossfire. Tracking the murder back to a ninja, Fujikido trains to seek vengeance: initially on those who murdered his family, but ultimately on every ninja on the planet.