"Ninja Kamui" is an anime series that centers on a former ninja named Joe Higan, who attempts to leave his violent past behind by relocating to America with his family. Seeking a peaceful life, Joe adopts a new identity and settles into a quiet existence. However, his past catches up with him when a group of assassins from his former clan tracks him down, brutally murdering his wife and son. This tragic event reignites Joe's resolve to seek vengeance against those who destroyed his life.

The narrative unfolds as Joe, now operating under the alias "Kamui," reawakens his dormant ninja skills to hunt down the members of his former clan. The story delves into themes of betrayal, loyalty, and the cyclical nature of violence, as Joe uncovers deeper conspiracies within the clan and its connections to a powerful, shadowy organization. The series explores the moral complexities of revenge, as Joe's quest for justice often blurs the line between right and wrong.

Key characters include Joe Higan (Kamui), the protagonist driven by grief and vengeance; Emma, a mysterious ally who aids Joe in his mission while harboring her own secrets; and the enigmatic leaders of the clan, who manipulate events from behind the scenes. The series balances intense action sequences with moments of introspection, as Joe grapples with the consequences of his actions and the possibility of redemption.

The plot is structured around Joe's relentless pursuit of his targets, interspersed with flashbacks that reveal his past and the events that led to his exile. As the story progresses, alliances shift, and new threats emerge, culminating in a climactic confrontation that challenges Joe's resolve and forces him to confront the true cost of his vengeance. "Ninja Kamui" presents a gritty, character-driven narrative that combines traditional ninja lore with modern storytelling elements, appealing to fans of action and drama.