The Guide is Actually a Body-Switching Esper [BL] - Chapter 16: Allergic Reaction

My name is Qin Jue. At only 16 years of age, I'm already the youngest person to ever become an uncle-grandmaster in the Xuanyi Mountain Sect.Also, I'm the strongest being in this entire world!But unlike other transmigrators, I want nothing to do with the outside world and wish to live a leisurely life on a cliff behind the sect, sipping wine and singing songs.That is until one day, a mysterious girl appears in front of my yard…Join Qin Jue as he deals with sneaky sects and greedy, hostile clans, all while raising a "weed" to sentience and creating heaven-defying spirit-energy "guns".

Thousands of years ago, a small planet collided with Earth and destroyed the world. In five days, ninety percent of humans had been wiped out, leaving behind the last ten percent to earnestly struggle on death’s door.

Jinyu was one of those people who survived. Due to a special heredity trait, he could understand beast language. After the apocalyptic disasters, Jinyu had been living for a month with the few small beast brothers that he’d subdued. Previously, Jinyu had thought that he would live like that until he died. Yet, inexplicably, one day he opened his eyes to find that he was in a monstrous, lawless world that was full of vitality and life.

Jinyu’s transmigration into the future let him skip over almost one hundred thousand years. In the year 106825, beasts rule the galaxies and ‘pure’ humans are extinct. As the one and only ‘pure’ human left in the entire universe, Jinyu braves this new chaotic world to find a place for himself and thus begins to work at Beast Store number 138.

- Description from Novelupdates

Eren Idril died as an old, decrepit, and piss-poor adventurer by the maws of a D-Rank monster. He had a lot of unfulfilled dreams and desires that couldn't see the light of the day after the light in his own eyes died down.

But fortunately for him and unfortunately for the world, that wasn't his end. Eren was somehow dived back in time when he was a mere teen, attending Lionheart Academy for adventurers.

When life gives him a second chance, Eren decides to exploit it to its fullest. Experience his vile deeds as he partakes in them without feeling the slightest bit of hesitation.