Koto "Kotono" Tateshina hails from the distant planet Karutei, where she once served as a miko (priestess). This sacred role endowed her with the abilities to sense spiritual energy and perform powerful exorcisms. Her non-human physiology grants her resilience, allowing her to consume foods that would be toxic to humans without suffering any ill effects.

She currently shares a residence with the protagonist Kazuya and several other female characters. Her specific reason for joining this household remains a mystery, though her arrival coincided with the establishment of the group's cohabitation arrangement.

Information regarding her life prior to joining Kazuya's home, any character development throughout official media, or backstory beyond her planetary origin and spiritual powers is absent.