Kai Tatebayashi is a character within the Taishō Mebiusline universe, affiliated with the Gohongatana Clan. This group opposes the Imperial Army in 1923 Tokyo. He possesses blonde hair and blue eyes, and wears a military-style uniform, boots, gloves, and an armband.

As a Gohongatana Clan member, he engages in conflicts involving supernatural elements and wields spirit perception. The narrative places him in confrontations focused on protecting the protagonist, Hiiragi Kyoichiro, who possesses the ability to see spirits targeted by the Imperial Army. Kai Tatebayashi navigates alliances and hostilities within the clan's struggle against military forces.