MTL - Please Spare Me a Tail - v2 Chapter 83

An anime otaku who has traveled to the world of full-time hunters, in order to live well, he can only keep getting stronger all the time, burying the strong one after another. Your withered life will be continued by me.

- Description from novelbuddy

A 30-year-old NEET is reincarnated into the body of an otaku that choked to death on instant noodles. As he comes to grips with his new life, he realizes that this world is subtly different from Earth. The denizens of this world are far better looking, and this new world also possesses futuristic technology as well as mysterious Yin Yang masters!

After reincarnating, he realized that he was endowed with a miraculous game-like system, which enables him to increase his own stats and transcend the limits of the human body. This system even has a game-breaking ability to save and load in real life!

In this new world that’s akin to a 2-D game, he just wants to enjoy life and head for a glorious future… However, he is quickly embroiled in a complex plot. Can he unlock his true potential and utilize his system to break the shackles that confine him and discover the truth about his previous body’s circumstances?

- Description from novelupdates

One day a young man found a mysterious door in his grand father house and that door transported him to Tensura....welcome to the new world...all the credit for the characters and main story goes to the owners, this is just a fanfic none of the characters or the storyline belongs to me...Tensura won't be live until later in the chapters, so if you in a rush, you can quick rocks...

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