Yamato Tachibana, a Japanese demon hunter and the narrative's central male character, is a teenage part-demon hybrid with purple eyes and green hair that reaches his ears, though some sources describe him with dark grey hair and blue eyes. He works alongside Mikoto Shiratori and her twin sister Takeru under their boss, the cat spirit Yoru. Sui Kayama, an old childhood friend, later joins their team as a fellow demon hunter. Yamato often finds himself in a love triangle between the headstrong, easily angered Mikoto and the shy, gentle Sui.

On his first documented mission, Yamato and Mikoto are sent to rescue Takeru from a haunted school, where they encounter Sui; together they exorcise the demons infesting the location. Though determined to protect his teammates, Yamato frequently ends in trouble and must be rescued by the stronger Mikoto, leaving him uncertain of his own abilities.

While in Mikoto and Takeru's hometown, Yamato confronts secrets involving the town chief and a demon named Azumi, who has ties to his past. In one narrative path, a demonified Yamato attacks and kills several unnamed female exorcists.

Other adaptations present different events: an OVA adaptation concludes with Yamato killed by a demon named Nightmare and Mikoto and Sui enslaved, though subsequent OVA sequels revert to the established status quo. He was also absent from the anime adaptation of the second story arc, in which only the female characters traveled to the resort island.