[From Ivyscan]:

Miruku gets the shock of her life when she finds a strange person in her bed one morning. Ruu claims to be an angel who has cast a spell on Miruku's family and schoolmates. In return for silence about her identity, Ruu agrees to help Miruku any way she can. One day, a student quarrels with the rest of the class. Ruu tries to put things right with a spell, but it doesn't seem to work on that student...