She's best known for her role as Ruka's devoted companion and blood donor. After losing her parents young and getting abandoned by relatives who wanted nothing to do with her, she found herself drawn to Ruka and essentially pledged herself to him as his thrall. It's a pretty committed arrangement—willing blood donation and all that comes with it.
To keep a low profile and dodge attention from others, she disguises herself as a boy. She and Ruka share a dorm room, which is pretty convenient given how close they've become. Fans often note that her backstory of isolation and family rejection sets up her intense loyalty nicely, even if the whole thrall dynamic is definitely unconventional.
Content compiled by AnimeList.moe from publicly available sources.
