I Have A Super USB Drive - Chapter 21: End of the Experiment

[You have entered the dungeon at Gwachun Station’s 1st Exit.] When former high school student Kang Woojin finds himself returned back to Earth after being forcibly summoned to a foreign planet for 20 years, he soon finds that Earth is not the same, normal place as he once remembered it to be.

At the end of a Dynasty filled with Demons and rampant Martial Artists, Lin Xuankong has unfortunately transmigrated to this era, becoming a poor and sickly old man. However, with the help of the system Life Plate, his Talent and Comprehension grow stronger the longer he lives.And his much younger wife is a martial master...“That iron ball used to be Zhang Wu's knife. I squeezed it a couple of times, and it ended up like this! ” said his wife.“I hope you can teach me some Cultivation Techniques. As for the reward...” said Lin eagerly.

Among the demons, the supreme ones are called “Great Saints.”

A young man leaves his mountain village and travels around the world. By unceasing efforts, he finally becomes a legend of the age.

- Description from Novelupdates

In this world, Planet Earth had undergone great changes and humanity is faced with extreme danger. Luckily, humans have something called the Heaven Dao software.