Ninjas were once revered as powerful rulers in ancient Japan, using their martial arts during peaceful times. However, a covert group practiced a forbidden harakiri ritual, hoping for future resurrection at Kinkaku Temple. Unfortunately, distorted history lost their knowledge.
But in a technological world, these malevolent souls have been resurrected and unleashed in Neo-Saitama's shadows. Fujikido Kenji, a salaryman who lost his family in a ninja war, encounters an enigmatic ninja soul after a close call with death. As "Ninja Slayer," he seeks vengeance by eliminating evil ninjas in the dystopian underworld of Neo-Saitama, battling Soukai Syndicate ninjas to the death.
