Seimaden 

How far will one man go for love? Find out in SEIMADEN, the tale of Laures, who agreed to become a demon in order to free his one true love Alice from a demon king! Laures became the next Demon King, and Alice was freed — with death. Laures, however, realized that his new inhuman status gave him a rare opportunity: by being the cruelest and best Demon King, he survived long enough to see Alice reincarnated, and then he would effectively be reunited with her. Laures, after living through the centuries, has finally found his beloved reincarnated as Hilda, a dancer who has no memories of her own past or identity. Now he must see if she will accept him as a creature of the underworld…