After Being Defeated, I Became a Demon Princess?

【Transformation】【Change Single】【Western Fantasy】 (After thinking about it, I decided to go single)

Aaron, humanity's greatest hero, fought the demon king Evelyn with all his might in the final battle, but failed. When he opened his eyes again, he found himself bound by Evelyn in a mysterious ritual. When the ritual was completed and he awoke, he discovered that not only was he not dead, but he had been transformed into Evelyn's daughter.