According to the MMORPG Cross Reverie, Sakamoto Takuma boasted overwhelming power that was enough for other players to call him the Demon King. One day, he was summoned to another world with his appearance from the game. There, two individuals insisted, "I am the true summoning master." Takuma was used by girls to summon monsters with a slave transformation spell—however, the strange ability "Magic Reflection" activates! The ones who turn into slaves are the girls! Takuma is shocked. He was the strongest magician, but had no social skills at all. In a panic, the first words that came out of his mouth were those of the Demon King role he played in the game. "Are you saying I'm amazing? Of course. I am Diablo... the feared Demon King!" The curtains rise on the story of the Demon King who will inspire this world and his adventures in another world with his absolute power!
