Kujibiki Tokushou: Musou Hāremu ken - Chapter 241

Quinn Winter is a young man from another world. One day, he is suddenly chosen to become the new Demon King. But the Demon Kingdom is in big trouble – it's losing a terrible war against the human kingdom called Gran'le.To help his people, Quinn comes up with a risky plan. He will sneak into Gran'le and learn their secrets. But things don’t go as planned. A powerful noble sponsors him, and he ends up joining Heavenward Academy, the top school for training future heroes.At the Academy, there's a big challenge called the Selection. The best students become Paladins – magic knights who fight demons. Quinn doesn’t want to become a Paladin. He is a demon king! But now, he’s stuck in the Selection… and if he wins, he’ll become the very thing he’s supposed to destroy.He started the day badly. Now, things are getting even worse.

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

Takahiro Nao, a 25-year-old drowning in debt and despair, lives only for his struggling family. Every sacrifice he makes is for them—until a selfless act costs him his life. Instead of the end, Nao encounters a Goddess of Benevolence who offers him a miraculous deal: “Live in a new world, and your efforts there will support your family back on Earth.”Reborn into the dead body of Naoki von Blackmore, the so-called “Failed Hero,” he finds himself burdened with the daunting task of saving the world by defeating the Demon King—all while supporting the family he cherishes. Armed with formidable powers yet haunted by his past failures, Nao steps into a dangerous realm of swords, magic, and ferocious monsters. Facing relentless enemies, harrowing trials of life and death, and an unyielding fate, he’s forced to confront the ultimate question: how far is he willing to go to protect the people he loves?Filled with emotional struggles, determination, unexpected humor, and a touch of romance, this story asks a powerful question to the readers: What would you sacrifice for the people you love?

“Send me to the past.” That’s how the first step toward revenge began.