Kenji Fujikido is a salaryman whose wife and child were killed in a ninja turf war. In a brush with his own death, Fujikido is possessed by an enigmatic ninja soul known as Naraku Ninja. Fujikido cheats death and becomes "Ninja Slayer" -a Grim Reaper destined to kill evil ninja, committed to a personal war of vengeance. Set in the dystopian underworld of Neo-Saitama, Ninja Slayer takes on Soukai Syndicate ninja in mortal combat.