Jine Udo, also known by the alias Kurogasa, serves as a primary antagonist in the first live-action film. He is a former hitokiri, or manslayer, from the Bakumatsu era, who has continued his bloody work into the Meiji period. Before becoming a hitokiri for the imperialist cause, he was originally a member of the Shinsengumi, the shogunate’s special police force, where he was known for his exceptional skill with a sword. However, his insatiable bloodlust led him to murder indiscriminately, even killing his own allies, which forced him to flee the group.

Jine Udo’s personality is defined by a profound and psychotic obsession with killing. He lives only for the sensation of taking life and the thrill of facing a worthy opponent, a feeling he believes has faded from the world since the end of the revolution. He is a cunning and sadistic manipulator, lacking any loyalty to ideology or employer, driven solely by his murderous impulses. His detached demeanor belies a deep, burning desire to re-experience the chaos and bloodshed of the Bakumatsu, viewing the Meiji era's peace as a personal insult.

His primary motivation in the story is to draw out the legendary Battosai the Manslayer, the former identity of the wandering swordsman Himura Kenshin. Jine finds Kenshin's current vow to never kill again disgustingly weak and seeks to provoke him into returning to his deadly true nature. He kidnaps Kaoru Kamiya, the young master of a Tokyo dojo who has formed a bond with Kenshin, intending to use her as a hostage to fuel Kenshin's rage and break his spirit.

Within the narrative of the film, Jine Udo acts as a dark mirror to Kenshin, representing the brutal past that Kenshin desperately tries to escape. His role is to be the catalyst that forces Kenshin to confront his inner demon. After initially clashing with Kenshin, he takes Kaoru captive, leading to a final, brutal confrontation. In their battle, he uses his techniques to push Kenshin to the brink of reverting to his Battosai persona. His key relationship is with Kenshin, viewing him as the ultimate target to satisfy his craving for a thrilling fight. He also has a brief employer-employee relationship with the corrupt businessman Takeda Kanryu, for whom he works as an assassin. Throughout the story, Jine remains a static character, unchanging in his madness. His development is instead a catalyst for Kenshin’s internal conflict. His story ends not with redemption but with suicide. After being defeated by Kenshin and refusing to be taken alive, he stabs himself, declaring that he will watch from hell to see how long Kenshin can uphold his no-kill vow.

As a swordsman, Jine Udo is a master of the Nikaido Heiho, a distinct style of kenjutsu. His deadliest technique is Shin no Ippo, a powerful hypnotic ability that locks the enemy's body in place by injecting a "sword spirit" through his gaze. In its strongest form, this technique can even stop a victim's lungs, causing them to suffocate in a matter of minutes. He can also apply this technique to himself in a practice known as Hyoki, or the "possessing ghost technique." By reflecting his own gaze in his sword blade, he can hypnotize himself into believing he is invincible, drastically increasing his physical strength and speed for a short time.