Akuma mo Fumu wo Osoreru Tokoro

Every 666 years, the ruler of the demon world changes. All the children of the former ruler must battle to see who will ascend the throne. To do this, these 'Satans' will team up with the human sorcerer 'Solomons' and fight in pairs. The Solomon of the winning pair is granted one wish. This 4-koma follows the story of one of those Satans, called Aini. Unfortunately, the human who summons Aini is actually just an erotic doujinshi writer who was doodling. He seems really into Aini, and he makes it clear his wish is going to be something (probably perverted) involving her. Their first battle is against another doujinshi writer, a girl who's really into tentacle porn. Since none of the Solomons have any skill with magic, they're going to have to find a different way to battle it out... (Source: MangaHelpers)