Kashitarō Itō, a historical figure reimagined within the narrative, serves as a central antagonist within the Shinsengumi’s rival faction, the Goryou Eji. Once aligned with the Shinsengumi, he defects after clashing ideologically, establishing his own group to support Imperialist efforts to dismantle the shogunate. His motivations center on unifying authority under the Emperor, rejecting his former comrades’ dependence on brutality and covert tactics.

Cunning and politically driven, Itō employs calculated strategies to destabilize the Shinsengumi. A pivotal moment occurs during a clash at Sumiya, where he attempts to ambush the protagonist, only to be intercepted by an ally’s intervention—an act highlighting his ruthless pragmatism and role as a morally ambiguous adversary.

His betrayal ultimately leads to his assassination by the Shinsengumi, a decisive event escalating factional hostilities. The narrative frames his demise as the inevitable result of his scheming and the volatile political climate. His younger brother, Miki Saburō, aligns with his faction, though their dynamic remains largely unexplored.

Adaptations consistently portray Itō as a symbol of Bakumatsu-era tensions, emphasizing the era’s conflicting loyalties and ambitions. His confrontations with other characters underscore the personal and ideological rifts shaping the series’ historical backdrop.