It turns out that my Yandere playmate online is my Homeroom Teacher - Chapter 16: She just stole my first kiss!!

In the tenth year after the new era, the world finally came to an end. Zhang Mu truefully waited for his death, but unexpectedly found that he had returned to ten years ago. With his memory about the future, he swore that he would change the calamitous history, saving the earth from being destroyed! Walking dead, zergs, evolvers, and various mutated animals… nothing can stop him! The first step is to retrieve his identity as an era merchant , then find all the treasures he can remember to enhance himself!

- Description from Novelupdates

In a world fraught with innumerable dangers where living day by day is a struggle, a young man from the modern age transmigrated into such a world, accompanied by a peculiar system made for assassination.

Earth Immortals are cultivated from a blessed land.

Heaven Immortals move to and from the divine mountains.

I have a stalk of plum blossom, and I shall plunder the Will of the Heavens with it!

- Description from Novelupdates