MTL - Fairy Tail: The Nameless Grim Reaper - Chapter 25 demon?

Wei Yuewu is the unloved daughter of the powerful Marquis Hua Yang. On her way back to the capital city to marry her fiancé, she becomes the target of a ruthless assassination led by her fiancé, Marquis Jing Yuan. With the help of the Prince of Yan State, she narrowly escapes from one disaster after another and returns to the capital. Determined to avenge her enemies and unravel the mystery surrounding her engagement with Marquis Jing Yuan as well as the death of her mother, Wei Yuewu makes a deal with the Prince of Yan State. However, just as she has triumphed over all her enemies and is about to reach the acme of her life, she deliberately destroys her own future and becomes an exile of her own…

- Description from Novelupdates

Year 2056, in a city in the Yuan Jiang Su Jin area. On top of a ruined, shattered six story residential apartment sits a teenager wearing a combat vest, militaristic trousers, and alloyed battle boots. On his back is a hexagonal shield and equipped is a blood-shadow battle knife. He sits there silently on the edge of the roof. At this time, the sparkling sky was shining and there was a refreshing breath within the air that blew towards him. However, there was only silence within the ruined, deserted city, with an occasional howl that makes your heart skip a beat.

Xuan Yi was transported into the fictional world and became an elder of the Black Sword Sect! The moment he entered the world, he was at the Sea-Splitting Rank!

“I don’t care what Thanos’ ideals are, and I don’t care what the consequences of having too many creatures in this universe will do, as long as he doesn’t ruin my business with that damn Infinity Glove!” – Kahn Ponte

Once he traveled to the world of American comics, Kahn had the golden finger to trade all worlds.

At this point, the name of Boss Kahn not only resounded in the Americas of the Marvel Universe, but his influence spread to all the worlds!

PS: There are many follow-up worlds such as Marvel, Naruto, Harry Potter, One Punch Man, Black Robe Pickets, Dragon Ball, Pirates, etc. You can decide…

- Description from novelbuddy