Protagonist's Evil System: My Girlfriend Turned Into A Dragon - Chapter 116 Another?

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.

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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

A university student is stuck working on coursework late into the night due to some unfortunate circumstances. After reflecting on the choices she has made so far in her life and looking forward to what she can do once she is finally able to really get her life going, she starts to make her way home.Unfortunately for her, that life is abruptly cut short, and she finds herself in a new world as a new person, one with a fluffy tail at that. She must come to grips with her new reality, no matter how bad it may seem. Luckily, a clumsy kitsune goddess seems to be looking out for her.This little kitsune will go on a journey to improve herself as she learns more about the world she now lives in, struggles through romance, and puts her life together.

When The Cute Kunoichis Spied on Their Teacher's Secret is a light novel written by Kazuma Kamachi and illustrated by Ryuushi Tajima.

The story takes place in a world where Japan never ended their isolationist phase, and agents from foreign powers are always threatening to steal the country's advanced technology. In order to combat this threat there has been a resurgence of ninjas that use Strategic Martial Arts, techniques that combine cutting-edge modern technology with a traditional foundation of martial arts and ninjutsu. The story follows Souha Sugiyado, a 17-year old ninja instructor and former ninja prodigy who was forced to retire from active duty by the wounds he suffered in his last mission. Souha's four students are all kunoichi who have all gained the rank of Elite Ninja, the highest official rank available to ninja. However, one day two Shogunate ninja approach him with the news that his four students have gone rogue and have stolen a portable modular nuclear reactor, and thus they ask for his help in bringing his students to justice.

Emperor Xianwu ninth reincarnation, only to break through the shackles, was besieged and killed by masters from all walks of life.

Fortunately, a ray of divine consciousness traveled across thousands of planes to the earth and entered the body of the dead young man, just to get rid of the anger in his heart and to regain that peerless peak!

- Description from MTL