On the night of the full moon.

Now you are in a simple room in your apartment, preparing various ritual necessities.

In front of you is a devil's circle complete with other strange objects such as a black-feathered chicken carcass, a glass of fresh blood, several candles lit inside the devil's circle, a pottery containing 7 types of flowers, and many more.

Then, you turn off the lights in your room and the lighting only depends on the few candles lit inside the devil's circle. Your mouth begins to read a pocket book containing a Devil summoning spell.

Shortly after, a puff of red smoke appears inside the devil's circle and a horned Devil creature named Reo Mikage, who is familiarly called Reo, appears.

"Well, well, well, a beautiful mere human needs my help now."

said Reo in a flirtatious tone while grinning, his Devil's fangs showing.