In the live-action film Rurouni Kenshin Part I: Origins, Jin-e Udou, also known by the alias Kurogasa, serves as a primary antagonist who directly challenges the protagonist's core principles. His background is rooted in the violent upheaval of the Bakumatsu, a period of civil war that preceded the Meiji Restoration. During that time, Jin-e was a hitokiri, a government-sanctioned manslayer, who fought for the Shinsengumi on the side of the shogunate. After the war concluded and a new era of supposed peace began, he continued his work as a freelance assassin, accepting contracts to eliminate high-ranking officials of the new Meiji government. His thirst for blood was indiscriminate; during the conflict, he was known to have killed members of his own squad, demonstrating a fundamental lack of loyalty beyond his own desires.

Jin-e possesses a cold and sadistic personality. He is defined by a profound and obsessive passion for killing, viewing it not merely as a profession but as a vital source of satisfaction. He takes genuine delight in the fear of his victims, savoring the terror in their eyes before he ends their lives. His central motivation throughout the film is to experience the ultimate thrill of combat. He is fixated on Himura Kenshin, the legendary Hitokiri Battousai, believing that a fight to the death with the manslayer in his prime would be the pinnacle of his existence. He holds no interest in fighting Kenshin in his current state as a wandering swordsman bound by a vow never to kill. Instead, his goal is to systematically dismantle Kenshin's peaceful life and psychological resolve to force the re-awakening of the Battousai.

Jin-e's role in the story is to act as a dark mirror to Kenshin's past. He is the physical embodiment of the violence Kenshin is trying to leave behind. His primary relationship is with Kenshin, whom he views as his ultimate rival and the key to his own gratification. To achieve his goal, he kidnaps Kamiya Kaoru, the woman who represents Kenshin's new, peaceful life. He uses her as a tool, understanding that her mortal danger is the most effective way to shatter Kenshin's non-lethal oath. Jin-e shows little direct interest in Kaoru beyond her utility as a hostage, coldly viewing her as a means to an end. His actions force the central conflict of the film, culminating in a final duel designed to test whether Kenshin will revert to his assassin persona to save a loved one.

In terms of development, Jin-e is a static character who does not change or learn from his experiences. He remains committed to his bloody philosophy until the very end. After being defeated in combat by Kenshin, who manages to tap into his Battousai abilities without breaking his vow to kill, Jin-e's arc concludes with a final act of defiance. Unable to live without his sword arm and refusing to accept a world where he cannot kill, he commits suicide by stabbing himself with his own wakizashi. His dying words reinforce his unchanging nature, declaring that a manslayer remains a manslayer until death.

Jin-e is an exceptionally skilled and dangerous swordsman, proficient in the Nikaido Heiho style of swordplay. His most notable and terrifying ability is a hypnotic technique known as Shin no Ippo, which translates to "One Side of the Soul." This allows him to project his killer intent or "swordsman's spirit" through his eyes. He can use this power in several ways: to paralyze an opponent completely, leaving them unable to move or defend themselves; to strengthen himself by looking into the reflection of his own sword and convincing his body it is invincible; and, in its most lethal application, to stop the lungs of a victim, causing them to slowly suffocate to death. In the film, he uses this ability on Kaoru, creating a desperate time limit for Kenshin to defeat him. This power makes him a uniquely terrifying foe who attacks both the body and the will of his opponents.