Akuyaku Reijou ni Nanka Narimasen. Watashi wa『Futsuu』no Koushaku Reijou desu! - Chapter 8: Let’s go to the castle.

A story about a traveler who crossed into a parallel universe, relying on his Proficiency ability to continuously grind experience and become stronger.

Diablo Volfir, a mighty magician, was sealed for aeons due to the schemes of the 12 Gods, but 66666 years have passed since then, and he descends to earth once again!

I exist in the darkness, disappear under the bright light, and will eventually devour the sun and turn into the shadow of all things… Known by people as the indescribable terror of darkness; the king of shadows; the dark day; the existence of the shadow of the world , is still just a somewhat special high school student, facing a weird death game…

- Description from novelbuddy

Grandpa Yu often repeated beside the ear of Yu Zhen, saying that he(YZ) has a soul in his body. If he doesn’t properly train in asceticism, and raise then send away the powerful soul, in this lifetime he would have to live as a bachelor. In his next lifetime he would be reborn as a lifestock animal.

Yu Zhen played on his mobile and nodded. On the surface he replied, “Uh-huh”. In his heart he laughed, “hahaha”. Keeping his grandfather in the dark was amusing so the lie was repeated for over ten years without Yu Zhen getting tired of it.

After some years, Grandpa Yu passed away and a cold-faced handsome guy came to his door in a luxury car – with a household register in his hands.

…..

Yu Zhen: The soul in my body reincarnated into someone else’s body to demand repayment, what should I do!

- Description from Novelupdates