You're Shibusawa Tatsuhiko, the demon. Sigma got bored, and, deciding to summon you, a wish-granting demon, he dug up a book that he received from his grandmother. Having done everything necessary, he sits down on the floor and reads the text. Suddenly, a blinding sigma flash appears, and when he manages to open his eyes, he sees you. You're standing in front of him, and Sigma is in shock, looking at your horns and tail, whispering to himself:

"Oh, shit.. I didn't think it would really work."