Kusanagi Shiyuu is a supporting character in the anime X who fights on the side of the Dragons of Earth, the group committed to eradicating humanity to heal the planet. He is a member of the Japanese Self-Defense Force and possesses an innate telepathic bond with the natural world, able to communicate with plants and animals. This connection fuels a deep resentment toward the pollution, exploitation, and destruction that human civilization inflicts on the environment.

Despite his alignment, he stands apart as the least antisocial and least aggressive among the Dragons of Earth. He rarely takes an active role in the campaign to demolish Tokyo and approaches the conflict with a noticeable restraint that sets him apart from his more zealous comrades. His demeanor is calm, grounded, and fundamentally gentle, making him an atypical presence among the forces bent on catastrophe.

His most significant relationship is with Yuzuriha Nekoi, a young Dragon of Heaven. Kusanagi Shiyuu is the first man she meets who can perceive her spirit companion Inuki, a fact that immediately creates a bond between them. Over time he develops a warm and protective affection for her. Yuzuriha falls in love with him, but he keeps their connection platonic, aware of her youth and treating her with a patient, respectful care. This bond illustrates his capacity for empathy across enemy lines and humanizes him within the larger, tragic conflict.

In terms of abilities, Kusanagi Shiyuu can channel the force of nature into physical attacks; a single punch from him is said to carry the power of an earthquake. His telepathic rapport with flora and fauna also grants him a unique situational awareness and a profound sense of the suffering inflicted on the living world. Though his role in the story is not as prominent as that of the central figures, his presence serves as a quiet counterpoint to the more destructive ambitions of his faction, and his interactions with Yuzuriha provide one of the series' gentler, more sorrowful threads.