Path of the Berserker - Chapter 4Book 3:

Transmigrating into a poor and mistreated young lady's body, what will the craziest alchemist of the seven realms now do?

Leiyin accidentally crossed into the One Piece World, and accidentally obtained the Naruto System.

Living in this apocalyptic world full of zombies and monsters, the rich rely on technology and the poor rely on mutation.

Shen Shanwu, 13 years old in appearance but 31 years old in reality, is a mutant that can alter his own appearance. Although he looks like a child on the outside, his wisdom is not very good. One day, he was just passing by when he was suddenly forcibly adopted by a major general, whom he didn’t know where he came from.

He resisted, but when he looked up, it turned out to be an old acquaintance.

The little boy, who could only hide behind him and cry, transformed into the unsmiling, cold, and tough man in front of him. And that expression of seeing a dead beloved is really unsightly…

Shen Shanwu: Can you smile?

Jing Huan: After Shanwu died, I couldn’t smile anymore.

Shen Shanwu: …Who? Who do you think is dead?

It took a long time before he found out about it. He found Jiang Huan crying and holding Shen Shanwu’s nameplate in the middle of the night and told his adopted son how good Shen Shanwu was… All of this…was seen by Shen Shanwu himself!

Jiang Huan (raising his gun): Since you have seen my embarrassing side, then I can only marry you or kill you.

Shen Shanwu: …

Shen Shanwu: Marry, marry, marry! I will recruit 800 zombies to carry you home!

- Description from Novelupdates

This story is about a rookie researcher, who was forcefully dragged away from his restful life, compelled into facing various killers and zombies, always having to risk his life at the brink of death, and finally becoming an advanced researcher that is acclaimed by all. And throughout his adventure, he met an alluring(?) killing machine, who he started to have fantasies on after they had an accidental kiss…

Xiao Yan: Did I fall for him? But he’s a man!

Maya: Who knows…. maybe it’s the other way round?

- Description from Novelupdates