Ninja Slayer From Animation

Kenji Fujikido loses his wife and child in a ninja conflict in Neo-Saitama. As the salaryman approaches death himself, a mysterious spirit called Naraku Ninja possesses him, giving him the power to survive and pursue the people responsible.

Taking the name Ninja Slayer, Fujikido turns his grief into a campaign against the ninjas terrorizing the city. Yet the force that saved him is no obedient weapon. Alongside fighting powerful enemies, he must struggle to preserve his own will against the violent presence sharing his body.