My Friend The Demon Queen

A girl named Kenth, who's always mistaken as a boy because of the name, met a demon. The Demon King actually, only at age 18. They both became friends instantly, always talking to each other about their species and what they are like. One day, the king knocked on Kenth's window as she opened it, she saw blood everywhere. The king was injured badly not knowing how he was injured. He was slowly dying but then, he gave all his powers to Kenth and now... She's the new royal demon. At first she could not handle it because of how much power she can hold and we appearance that might frighten her friends so she instead hides it. Her new life became a whole different story with whole new enemies who wants her power... Will she survive?