Ninja Slayer is a series of novels which follow Kenji Fujikido who vows to hunt down and kill ninjas after his family is slain during a ninja battle. The stories are set in the futuristic city of Neo Saitama.
When a salaryman's wife and child are slain in a ninja war, he fuses with a supernatural entity to take vengeance on all ninjas.
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.