Martial King's Retired Life - Chapter 81Book 15:

Qin Tian accidentally transmigrated into a sickly body, a body with broken Dantian that was unable to practice Qigong, in another world. Fortunately, God had mercy on him by giving him a level up system. Useless? That was him in the past. Not worrying about practicing Qigong, he was now able to kill Monsters to level up. Easy! Level up when killing Monsters; level up when killing people. An unbeatable sovereign of the clan in the eyes of other people, but in his eyes, he is a glittering big BOSS.

With this level up system, he will no longer encounter any bottlenecks during a breakthrough in cultivation like other geniuses; all he needs to do was kill as many monsters, clan heads, sovereigns, world experts … to have a better life.

Dedicating his life on a road to become an expert.

- Description from Novelupdates

He is the master of six kingdoms. As long as he wanted, his cavalry is ready to wipe off any country.

King Grey has unrivaled strength, wealth, and prestige in a world governed by martial ability. However, solitude lingers closely behind those with great power. Beneath the glamorous exterior of a powerful king lurks the shell of man, devoid of purpose and will. 

Reincarnated into a new world filled with magic and monsters, the king has a second chance to relive his life. Correcting the mistakes of his past will not be his only challenge, however. Underneath the peace and prosperity of the new world is an undercurrent threatening to destroy everything he has worked for, questioning his role and reason for being born again. 

I made a character gacha game with constellations that people from other worlds can relate to. I was worried about what would happen if the constellations got angry, but… [The King of All Demons complains that the Demon King character’s pick rate is too low and begs for some fan service content.] [The First Elven Hero asks when their episode as the protagonist will be released.] [The Master of the Night fidgets their fingers, wondering if their character’s jaw could be made a bit more slender.] They… unexpectedly like it?