Even If It Were a Demon, Would You Still Like It?

The world has inexplicably changed; Mai Sakurajima, Misaki Shokuhou, and Misaka Mikoto suddenly appear. Why can he still connect to another world? The Holy Grail War; the Apocalypse Virus; the labyrinth city of Orario; the Teigu users; "The world is so chaotic, since I've become a demon, I should be cunning, cruel, and tyrannical, that's how it should be..." But these girls before him are not only not afraid of him, but their faces light up with joy upon seeing him; the demon falls into deep thought...