"Ninja Slayer From Animation" is set in a dystopian future where ninja clans, known as Soukaiya, dominate society through organized crime and cybernetic enhancements. The protagonist, Kenji Fujikido, is an ordinary salaryman whose life is shattered when his family is killed during a ninja conflict. After being fatally injured in the same attack, Kenji is resurrected by a mysterious ninja spirit known as Naraku Ninja, who merges with him. This fusion transforms Kenji into the Ninja Slayer, a vengeful warrior dedicated to exterminating the corrupt ninja clans.

The narrative follows Kenji’s relentless quest for vengeance as he battles various Soukaiya factions, each with their own unique cyber-ninja abilities and agendas. Along the way, he encounters allies such as Yamoto Koki, a former ninja turned informant, and Nancy Lee, a skilled hacker who aids him in his mission. The series explores themes of revenge, justice, and the moral ambiguity of Kenji’s transformation, as his humanity becomes increasingly intertwined with Naraku Ninja’s destructive influence.

The plot is episodic, with each arc focusing on Kenji’s confrontations with different ninja clans, including the Laomoto Khan, the Kage, and the Dragon. These battles are characterized by intense, stylized action sequences and a blend of traditional ninja lore with cyberpunk aesthetics. The series also delves into the origins of the Soukaiya and the shadowy forces behind their rise to power, gradually revealing a larger conspiracy that ties Kenji’s personal vendetta to a broader struggle for control over the ninja underworld.

"Ninja Slayer From Animation" is notable for its unique visual style, which combines retro anime aesthetics with modern digital animation techniques. The dialogue is often delivered in a dramatic, over-the-top manner, reflecting the series’ roots in pulp fiction and its homage to classic ninja and cyberpunk genres. The story maintains a fast-paced, action-driven narrative, with occasional moments of dark humor and introspection, as Kenji grapples with the consequences of his transformation and the toll it takes on his humanity.