Hoshi Tamura is a straight A student, captain of every sports team and an amazing exorcist. But she also is a demon, a water demon to be exact. She usually isn't very social and she doesn't have any friends until she meets the two sons of Satan. Won 3rd place in the 2015 anime watty awards for Blue Exorcist

15 years ago, Shiro Fujimoto made a mistake. He took in the two sons of Satan and raised them as his own (human) boys. Taking these demon children in was not his mistake. The mistake was that he missed one. That night, Yori died still carrying a child of Satan. But this child was not another boy. Yori and Satan had a daughter. IMPORTANT NOTE: This is based off of the anime, NOT the manga. It also contains spoilers for the anime.