In the MMORPG Cross Reverie, Takuma Sakamoto is so powerful that he is lauded as the “Demon Lord” by other players. One day, he is summoned to a world outside his own, but with the same appearance he had in the game. There, he meets two girls who both proclaim themselves to be his Summoner. They perform an Enslavement Ritual to turn him into their Summon, but that’s when Takuma’s passive ability Magic Reflection activates. Instead, it is the girls who become enslaved. Though Takuma may be the strongest Sorcerer there is, he has no idea how to talk with other people. It is here he makes his choice: to act based on his persona from the game.

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!