The girls seemingly don't actually have parents, though. Yukari is the only one, that I can recall, ever mentioning a family. She's a member of the prestigious Kadenokouji line, but she never mentions parents, and the only NPC related to her we see is a servant, and the only unseen NPCs related to her we hear about are also servants.
No one else has a family or any sort of guardian. The only familial relations any of them have are the occasional sister. They all live alone, answer to no one, and the only adult supervision any of them have besides Sensei is the extremely rare school staff. The only one of those I can even remember seeing was a one time swim class supervisor when Mika was being bullied.
