My Fusion System: Fusing a Thousand Chickens at the Start - Chapter 13

Xue Xi is forced to fall in love at first sight with this dangerous man on their first meeting. With death being the only other option, she makes the first move:

I, Lin Yun, with my exceptional aptitude, had thought that I would be trained as a key disciple, however...“The Demon Sect will never expect us to send such an excellent disciple undercover. Once you attain a high position within the Demon Sect, with our help both from within and without, why would we worry about the Demon Sect's destruction?”Three years later.“The Righteous Path will never expect us to send such a promising disciple undercover. Once you attain a high position within the Righteous Path, with our help both from within and without, why would we worry about the Righteous Path's destruction?”Lin Yun: I just want to quietly cultivate to immortality...

A modern-day antihero, who was infamous for his devious acts, dies in an explosion meant to take down a powerful criminal syndicate. Waking up in a world of sword and sorcery, he finds himself possessing a fragile, powerless body with a strange “System” that seems broken. Initially thinking he's doomed, he learns that by pretending to be weak, he can manipulate others into revealing their secrets, granting him abilities they possess. As he rises in power, he discovers that the System was intentionally sabotaged—by none other than his own future self.

Wang Yi gets a key, opening a door in 2022 will lead to 1982, and opening a door in 1982 will return to 2022.

Two very different great eras appeared before him:

Abundant dietary protection, developed industrial products, miraculous medicines, and explosive information, this is 2022.

Simple folk customs, rich wild resources, scattered antiques, and treasures of the age, this is 1982.

Traveling between these two eras, Wang Yi didn’t think much of it, he just wanted to live a good life.

- Description from novelbuddy