MTL - The Law of the Silent Gentleman - Chapter 23 Ambush in the woods

Leon was once an ordinary man—until he died saving children and woke up in a new world as the last prince of the demon race. But his awakening comes with a cruel truth: the war is already over.The Demon King is dead. The once-mighty demon empire lies in ruins. And now, Leon stands amidst the ashes, surrounded by a handful of survivors teetering on the brink of extinction.Crowned Demon King by default, he holds the title—but there is no kingdom left to rule. The few remaining demons are barely surviving, hunted and outnumbered. Worse still, Leon, who once enjoyed the luxuries of modern technology, must now navigate a harsh world stuck in the Middle Ages.Can he pull the demon race out of their misery? Can he reclaim the power they once held? Or will history remember him as the last king of a fallen race?Follow Leon on his journey to rebuild, conquer, and defy fate itself.

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 –

A black pearl brought Jiang Feng from a doomsday stage where top masters with one emperor, two emperors, three emperors, four deities, and seven peerless cities show off their glory to parallel time and space, and this time and space-the end of the world has not yet opened! !! Under the sky, the youth look up, if I have strength, can I get through … these two time and space! !!

- Description from 69shu

He became the villain in the possessed game, the rival of the main character, and the second seat.