Rakuin no Monshou - Volume 1, Chapter 2: Two Boys

Ling Fei, the son of a fisherman in Sanxian Island, was accidentally involved in a mysterious continent–Arad, after learning that his celestial destiny was shallow and that he had no way to ascend.

Sword, there are unique adventurers here. Ling Fei, who has just arrived, has a mysterious mission and an ancient blood. The silent Grand Forest is roaring, the ancient ruins of the king are lamenting, and it is unknown what the legendary headless horseman is chasing.

On the ground, Ling Fei gets acquainted with his partners, takes risks, and becomes a legend!

- Description from novelbuddy

Su Ran, a music prodigy, woke up transmigrated into a book.

At that point in time, the main story arc in the book had already been completed. As a villainess female supporting character, not only did she need to take over the original owner’s pitiful life in poverty, she also gained an instant son right at his rebellious period.

Ten or so more years from then, the son would turn into a twisted, evil villain. He would appear in one of the extra chapters to pick on the male and female lead’s children.

***

Su Ran: Son, you shouldn’t be too outstanding.
Su Han: Why not?
Su Ran: ’cause you will be killed.

Su Ran: Son, would you like to learn music from me and become a zen, little fairy boy who only needs to drink dew.
Su Han: No, I want to go into business so I can support you.

- Description from Novelupdates

Mochizuki Touya, a 15-year-old boy, who got zapped by a flash of lightning due to a freak accident caused by God, wakes up and finds himself face-to-face with God.

“From today onwards, you will become the Envoy of one of the Main Gods in the Dimensions of Gods. You will travel from one world to another and through that, you will attain what others will never obtain in their entire life.”

The moment these words echoed in Fang Li’s head, Fang Li’s life was destined to be extraordinary…

- Description from novelupdates