ガウェイン

"I-I'm not a child! At least treat me like a lady!"Gawain turns into a small girl at night. In order to hide this condition from others, she never leaves her room at night, but it's already widely known. If she ever goes out when she's a small girl, she always gets hit on by weird people, so she has taken it on herself to rid the world of deviants.[From English official site]