Sakamoto Takuma was so strong in the MMORPG Cross Reverie that his fellow players came to call him the "demon lord." One day, he gets summoned to another world in his avatar form, and meets two girls who both insist that they're the one who summoned him. They cast a spell used to enslave summoned beasts on him, but that activates his unique ability, Magic Reflect, and the girls end up being the ones put under the spell! And thus begins the otherworldly adventure of a demon lord (pretend) who blazes his own trail through overwhelming power.

Diablo (real name: Takuma Sakamoto), who has been summoned to a different world in the game, is in a different world that looks exactly like the game with Shera and Rem who insist that "I am the summoner" . I was spending my days. Fight the elite troops of the Elven Kingdom, fight the demons, and subdue the resurrected Demon King Krebs Krumm. While playing the Demon King, "I am Diablo. I am the Demon King of a another world!" , Diablo confronts the strong enemy, and while being at the mercy of the beautiful girls, he has built a solid relationship of trust. ── One day like that. Diablo and his friends go out to the forest of Koto and meet a girl who has fallen into disrepair . "Or God ..., is that?" It was Lumaquina, the chief priest of the church , chased by the Holy Knight ...! The Demon King (acting) with zero communicative competence pushes forward with absolute strength! The Unfolded Adventure by the Demon King from Another World and the summoned girls , continue again!