Seiken Gakuin no Maken Tsukai main character.
The Undead King and Strongest of the Dark Lords, Leonis awakens in the body of a ten-year-old child one thousand years in the future. With the help of Riselia Ray Crystalia (whom he and Regina Mercedes affectionally call "Selia"), Leonis begins adjusting to his new life but Leonis also has plans of his own, including fulfilling the wish of his benefactor, the Goddess of Rebellion.