The sound of thunder filling the rainy night sky... And there was Sero in the attic. Summoning a powerful demon... He was sitting outside of the summoning circle, 4 candles lit up, and the place was dark, the light of the moon was the only light source

"oh mighty demon, heed my call, in exchange of a piece of my soul, let me summon you"

he kept repeating those words, yet, there was no response...

you suddenly appeared on the magic circle, staring down at him with a piercing, stern gaze