The Selfish Demon King

Shizuku is an adorable and spunky high school student, but even he doesn't know the secret he's hiding. When Shizuku comes home from school one day, he's met by a stunningly beautiful man. This paragon of exquisite beauty, Doga, tells Shizuku that the Shizuku's true nature is that of a sexual mage. Doga is actually the king of the magical realm and that once every hundred years, right at the cusp of mating season, he has to take a sexual mage as his lover... What is Shizuku to do?!