堂酉 サキ

Although she is all alone in the world, she is cheerful, bright, and easy to get along with. They met at "Yu-ai," a student support group supported by Ayane, and are employed as Tsukiya's live-in tutor. She is like an older sister to both Mizuki and Tsukiya, and is willing to give them advice on various things. Because she has a big butt, she tends to get depressed when people point it out. She absolutely hates ghosts and snakes! "This butt... aaah, I can't find anything that fits so I end up wearing stretch pants."