Ryunosuke is a skilled swordsman who has been trained in the art of killing since he was a child. He works for a powerful clan, but his lack of morality and ruthlessness make him a liability. He is also haunted by a traumatic incident from his childhood, and his mental state deteriorates as the film progresses. He becomes increasingly violent and unstable, leading to a series of brutal confrontations with his enemies and allies alike. The Sword of Doom is a dark and nihilistic meditation on the nature of violence and the human psyche, and it features some of the most realistic and intense sword-fighting scenes in cinema history. The film's grim ending is a reflection of the pervasive sense of despair that pervades the story.