Deathworld Commando: Reborn - Chapter 86: Vol.4 - The Iron Grip.

Li Xuan traveled through the world of immortality and opened the apprentice system, and both apprentices and apprentices could be rewarded for upgrading.

【Ding! Accepting apprentice Qin Yue, reward you: Innate Divine Power]

【Ding! Accept the apprentice Zhao Tian, ​​reward you: call the wind and call the rain]

【Ding! Apprentice upgrade, reward you: space shuttle]

….

Li Xuan, who accepted a bunch of apprentices, evolved infinitely in seclusion.

Ten years later, the Devil Emperor invaded and wanted to sacrifice the whole world, but no one could stop it. The disciples watched the world fall into despair in pain.

At this time, Li Xuan appeared and slashed a sword against the Demon Emperor under the watchful eyes of the public.

Boom!

The sky fell apart, the invincible Demon Emperor fell on the spot, and the entire dark world was swept away by a sword.

The disciples were horrified. It turned out that the strongest person in the world was actually the master who had been in seclusion for ten years.

- Description from novelbuddy

Yun Bixue is in dire straits—

Being sucked into a fantasy world that nobody leaves doesn't sound half bad to Cain. He was a high school dropout with a drinking problem, living off disability due to his poor health, so it's not like he had much to lose except a few faithful friends he didn't talk to enough.

After a long night of drinking, Cain wakes up looking at what he believes to be the character creation screen of one of his beloved virtual reality games, but with no recollection of having purchased it. His unwitting choice to use the Random Character Creation option, unaware that the choice would be irreversible, sends him into this new world as a Puppet Master, a Summoning based class nobody else in the starting zone has ever heard of.

But as he soon realizes, this is no game, him and hundreds of others have been brought to another world with no instructions, no clear goals and no way home. It's a second chance to live a good life, but what will Cain be able to make of it?

The Special Investigations Unit is a covert organisation that no-one in the city knows about, dedicated to investigating bizarre occurrences beyond the comprehension of the living. The Chief Zhao Yunlan isn’t a simple guy either, being the inheritor of the Guardian Order, he has always been a righteous conformist, excelling between realms of the living and the dead. While investigating a school suicide case, Zhao is attracted to the calm and reserved Professor Shen Wei, but the Professor seems to be rather fickle towards him…

- Description from Novelupdates