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! “Amazing? But of course... I am Diablo, the being known and feared as the Demon Lord!” So begins a tale of adventure with an earth-shakingly powerful Demon Lord (or at least someone who acts like one) taking on another world!

Acting out the part of a Demon Lord, Diablo accepted a quest from the King of Lyferia. However, after befriending the kobolds he was meant to dispatch, he faces off against the Kingdom of Lyferia.But that situation is changed in the space of one night, because of a shocking decleration of war from the Empire of Gelmed!The enemy lays waste to a citadel city with overwhelmingly powerful Magimatic Sols, conquering it. Diablo, on the other hand, runs into an entirely different kind of crisis."Erm... Diablo... I, uhm, saw it.""Huh?""I saw what you... did in the courtyard with Solami... last night."This is the twelfth volume of the adventures of an earth-shakingly powerful Demon Lord (or at least someone who acts like one) taking on another world! The start of a huge plot twist!