Takayama Maria

Maria is the supervising teacher of the Neighbors Club; she is a ten-year old nun. While not unintelligent, she is often rude and immature and refers to others as "Rotten mandarin." She develops a sibling-like relationship with Kodaka who regularly makes her packed lunches, and is affectionate with him. She is also gullible, which Yozora uses to her advantage. [spoiler]It was later on revealed that she was never a teacher nor a nun at the school, which almost causes the club's disbandment if it weren't for Sena's intervention, who called up her father to appoint her as a special part-time teacher.[/spoiler] (Source: Wikipedia, edited)