Shizuko Amaike
Shizuko is the caretaker of a certain church on the island, as well as the one in-charge of the female side of the school dormitory. She is always wearing a sister outfit. Her Christian name is "Margarita", while most students address her as "Sister Amaike" instead. She is typically sister-like and a no-nonsense type of person most of the time, however she is also known to be very scary when she loses her temper. Kohei fears her as "The Person who cannot take jokes". Kanade calls her "Maru-chan" and Iori calls her "Shizuko-chan", which she doesn't seem too happy about.