Hime Muko

Yamato lost his dear childhood friend Shiki, who was sacrificed during a ritual. His unrequited love became an obsession; he refused to believe that Shiki was dead, and many years later he finally managed to search for him in the sacred palace forbidden to men, where he learned a terrible secret.
Shiki was kept alive and made to inherit the superhuman power that will make him the king of the country. Yamato swears to repress his feelings and follow Shiki as his servant, but...
(Source: Tokyopop)