Leviathan of the Covenant - Volume 3, Chapter 1 - The World Where There Are Dragons

He Lang died by his own hands for the sake of his imperial younger brother’s ambition, whom he loved. He was offered to be reborn in exchange for giving up his past romantic feelings. Reborn without the burden of his romantic feelings, he brings with him a manual to new worlds. He wholeheartedly followed the instructions of the manual to complete the tasks, not knowing that the originally slag gong was blackening…
He pleaded to his affectionate Emperor brother to release him, he pleaded to the paranoid prisoner next door, but until the end he remained baffled.
In the end, he discovered that the full name of the manual was – “Slag Shou Cultivating Manual”
Σ (っ ° ° °;) っ!

- Description from Novelupdates

The Age of Celestials has arrived.

In the world where Vincent was sent into, the existence of Celestial Beings greatly stimulated the advancement of humanity. With their help, the humans started breaking out of their shackles as they exceeded the limitations of their mortal bodies.

They have passed down mana cultivation techniques and various combat arts increasing their strength as they fought against the true enemies of the world…

However, as Vincent was sent by his grandfather to complete a very unusual mission, he learned that these majestic Celestial Beings weren’t gods or existences out of his reach… They were actually tools or weapons that humans have been using for their own greed. More than that, he discovered the true origin of the Celestials!

Hence, with the help of his System, he mounted a rebellion…

As an ordinary human being on the earth, Tang Long was brought to the Cultivation World by a lost immortal, and relying on his amazing talent, he made it to one of the five emperors in that world. However, struck by Thunder of Nine Heavens, he lost his life. It was lucky for him to transmigrate in the human world in an intern who was named Qin Haodong. With his excellent medical skills, he became a divine doctor of traditional Chinese medicine and encountered the baby girl he made before going into the Cultivation World, whose mother was as pretty as a fairy. The little girl even asked him to find more lovers. What a cute girl…

- Description from Novelupdates

As a promise, he went out into the world as an assassin. 3 years later, after becoming the Supreme Assassin, he gave up on everything he had and returned to the ranks of ordinary people. But one day, Kismet, a mystical game created by the National Research and Development had appeared.