MTL - The Divine Martial Stars - ~ 1341, I will replace you.

A girl who calls herself a demon appeared before a timid student named Fumio Kijima. The girl claims to be a campaign girl from the demon world and she gives him the ability to “summon a room” from nothing but thin air.

At first he doesn’t abuse his power and uses it as a convenient ability in his every day life. But one day he is bullied by his classmates under a false pretext and is made to suffer. In the past he would have wallowed in misery and cried himself to sleep, but now he had a power to call upon.

“I will make them regret it!”

Using his powers to summon his “room”, he begins his era of confinement and brainwashing to achieve his goals.

He died on the wedding of the girl he had a crush on, after a long and successful career. After convincing Yama to send him back to the world, he decides to fix the areas in which his life went wrong. Realizing the lack of love and romance in his past life, he sets out to conquer the hearts of various women.

- Description from Novelupdates

This novel is also known as I Possessed a Demon Sovereign

Chen Luoyang felt that something was wrong with his transmigration. After transmigrating, he possessed the body of the highest expert in the world, the Master of the Demon Cult, addressed respectfully as the Demon Sovereign.

Generally, aren’t supreme experts the ones that leave behind a wisp of their soul behind and occupy a new body of some miserable low-level youngster then they go on a journey of revenge and make a comeback?!

Or perhaps it would be transmigrating into a miserable youngster’s body and obtaining a cheat slowly walking the road to becoming a God?

But why did his transmigration seem wrong?

Now my environment is full of big shots and I feel like I’m going to be exposed!

- Description from Novelupdates

The world is up for sale, and Robin is making an offer.When Robin Waybright became the Merchant Hero, all of Pangeal turned into his marketplace; for the Merchant can buy and sell anything. Youth, skills, memories, hair color, joys and illnesses… in the trade of power, every deal can tip the scale.And Robin needs power. His homeland of Archfrost teeters on the brink of collapse, the sinister Demon Ancestors plot in the shadows, and twenty-one other Heroes, each with their own Class, have been chosen to save the world of Pangeal. Not all of them are friendly. There’s work to do… and profit to make.Cover by Dinovoila and Gharbi Zouhayer.