Manga by author Murasaki Yukiya

In regards to the MMORPG Cross Reverie, Sakamoto Takuma boasted an overwhelming strength that was enough for him to be called the Demon King by the other players. One day, he gets summoned to another world with his appearance in the game. There, there are two people that insist, "I am the real summon master." Takuma gets slave-turning magic used for summoned beasts cast on him by the girls - However, the peculiar ability Magic Reflection was invoked! The ones that were turned to slaves were the girls! Takuma was bewildered. Hethe strongest magician but, he doesnot have any communication skills. Panicking, the first words that came out were the ones that he used inside the game role playing the Demon King!? "I am amazing you say? Of course I am. I am Diablo... The one feared as the Demon King!" This is the story the Demon King (acting) that would soon inspire the world and his other world adventure that he plunges through with his absolute strength, raise the curtain!

Regis Ulrich is an incapable soldier; bad at both sword and archery, who passes the time by only reading books. While transferring to a remote region post, he meets a girl who turns out be the red hair and crimson eyed princess Altina, the wielder of the great sword "Grantneil Catoll." Despite being only fourteen years old, she was appointed to become the commander of the army in this remote region simply because she was the illegitimate child of the Emperor. However, she continues to pursue her dream of becoming Empress despite the circumstances that surround her. To achieve this goal, she asks Regis to become her tactician and stand alongside her against the obstacles they are sure to face.

When it comes to the fantasy MMORPG Cross Reverie, none can match the power of the Demon King Diablo. Possessing the game's rarest artifacts and an unrivaled player level, he overpowers all foolish enough to confront him. But despite his fearsome reputation, Diablo's true identity is Takuma Sakamoto, a shut-in gamer devoid of any social skills. Defeating hopeless challengers day by day, Takuma cares about nothing else but his virtual lifethat is, until a summoning spell suddenly transports him to another world where he has Diablo's appearance! In this new world resembling his favorite game, Takuma is greeted by the two girls who summoned him: Rem Galeu, a petite Pantherian adventurer, and Shera L. Greenwood, a busty Elf summoner. They perform an Enslavement Ritual in an attempt to subjugate him, but the spell backfires and causes them to become his slaves instead.With the situation now becoming more awkward than ever, Takuma decides to accompany the girls in finding a way to unbind their contract while learning to adapt to his new existence as the menacing Demon King.