Tadanori Sanbe is a second-year Yamakita University student intensely focused on physical strength and martial prowess. He rejects modern conveniences like cell phones, deeming them unmanly, dedicating himself solely to becoming stronger through combat. His appearance features short black hair and multiple scars, including a prominent vertical scar over his right eye and a larger scar from a past gunshot wound. His transformed state manifests as a large, skeletal monster with elongated arms ending in blade-like structures beyond the elbows, and shoulder areas resembling protective pads. Sanbe gained this transformation after an encounter with an alien entity where he wished for unmatched strength. His monstrous form grants enhanced durability, allowing him to withstand ordinary bullets, and significant physical power. He developed a unique martial art tailored to his non-human physiology after traditional techniques failed. One signature maneuver involves embedding his blades into the ground, bending backward, and unleashing a powerful forward strike capable of creating massive craters. Personality-wise, Sanbe adheres to a strict code of honor. He refuses to fight women, considering it dishonorable, and seeks battles only to test his strength, not to collect the alien coins others covet. Despite his combativeness, he displays calmness and respect towards worthy opponents, acknowledging their tactics and resilience. His story begins when he encounters Shuichi Kagaya and Clair Aoki in a forest. He engages them seeking combat but underestimates their teamwork. Clair's strategic use of Shuichi's abilities leads to Sanbe's defeat, though he survives due to his resilience. Upon awakening, he agrees to ally with them after Clair proposes cooperation would offer more battles against other monsters. This alliance stems from his respect for Shuichi's willingness to sacrifice himself during their fight, an act Sanbe deemed true masculinity. Within this alliance, he assists Shuichi and Clair against other threats. His loyalty is demonstrated when he kills another monster attempting to blackmail or enslave the group, viewing such tactics as disrespectful.