I read or watched it about a year ago or half and only remember the beginning. The main character has white hair and goes to a demon school. An angel has snuck in to the school but gives her self away by his cooking muffins or some type of dessert. She then wants to cut his hand so she could make that type of dessert in heaven.
The demon king or whatever he is called made the devils go to school because the angels kept on winning questions from God or something like that.