The Dragon, The Devil, and The Deviluke

Issei Hyoudou: pervert, older brother, pawn to the Gremory family heiress, future Harem King, and...King of the Universe? I'm pretty sure that one is a mistake. The young devil had life going pretty well for him, but, his life and his entire family and friend's lives were all changed, whether for better or worse, with the appearance of a pink haired alien in his bathtub.