Seimaden

A man named Laures becomes a demon to free his lover, Alice, from the demon king, only for her to be released through death. As the new Demon King, Laures discovers that his immortal existence offers a chance to reunite with Alice once she is reincarnated. After many centuries, he finds her reborn as Hilda, a dancer with no recollection of her past. Laures now seeks to determine whether she will accept him as a being from the underworld.