Korakage is a Koga ninja and the main antagonist of the film. He hails from the Koga clan, a historic rival of the Iga ninja, and is infamous for using a venomous dart that can instantly incapacitate or kill his targets. Displeased with the way many Koga ninjas have abandoned their traditional warrior lifestyle to blend into modern society, Korakage views them as traitors and sets out to punish them by attacking them with his poison weapon.

Ruthless and uncompromising in his mission, Korakage shows no hesitation in harming former allies or innocent bystanders. He orchestrates a series of attacks on Koga ninjas, causing widespread alarm. To lure his primary opponents into a trap, he kidnaps Kenichi Mitsuba, the young friend of the Iga ninja Kanzo Hattori. This act forces Hattori and Kenichi’s other protector, the Koga ninja Kemumaki, to confront him directly. Despite his fierce nature, Korakage possesses a deep-seated sense of ninja honor; after being defeated in combat by Hattori and Kemumaki working together, he is impressed by the strength of the friendship between Hattori and Kenichi. In a final act of remorse or respect, he gives Kemumaki a scroll containing the antidote to his poison and then perishes by setting fire to his own hideout.

Within the story, Korakage serves as the central threat whose actions drive the plot forward. His key relationships are defined by conflict: he was once a comrade of Kemumaki but now despises him as a defector; he has no prior connection to Hattori but becomes his sworn enemy; his brief interaction with Kenichi is that of captor and captive, yet it ultimately influences his change of heart. Over the course of the film, Korakage moves from being an unrelenting villain to a figure who acknowledges the value of bonds he initially rejected, culminating in a self-sacrificial redemption.

In terms of abilities, Korakage is a highly skilled combatant and a specialist in poison darts, which he uses with deadly accuracy. He is also adept at stealth and ninja techniques, enabling him to challenge Hattori directly in physical confrontation. His knowledge of poisons extends to their cures, a skill he ultimately uses to absolve the harm he caused. His lethal arsenal and unwavering dedication to his code make him a formidable adversary.