Yuika Koga

Yuika is a first-year student and assistant librarian with Keiki. She is one-quarter Caucasian, has blonde hair and blue eyes, and is initially shy and stand-offish, but warms up to Keiki's persistent attempts to get to know her. She's secretly a sadist who wishes to make Keiki her slave. She found out about Sayuki's fetish the first time they met and has been fighting to "protect" Keiki from the "Witch's" clutches.