I Alone Level-Up (Web Novel KR) - Chapter 164

He is a young man without a spirit root. It is believed that this denies him the chance at cultivation. However, a mysterious lady imparts a Supreme Demon Classic to him and from then on, he starts his path of cultivation.
He undergoes a total transformation to emerge as the most fearsome and powerful fiendish demon in his era, that even immortals and fiends are fearful of him, and saints are at his beck and call.
Mastering the Supreme Demon Classic is the turning point in his life. He is able to unleash his immense and divine power from within, illuminating the entire universe!

- Description from Novelupdates

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

[Palace Intrigue + Sweet Doting + Not Purely Chaste + Heroine Focused on Her Career]

On the first day of her transmigration into the imperial harem, Jiang Xinyu was already out of favor.

Everyone said she was merely a pretty face without substance.

On the second day of her transmigration into the imperial harem, Jiang Xinyu regained the emperor’s favor.

From then on, she held the emperor’s heart firmly in her hands.

She fought monsters and leveled up, rising from a noble consort all the way to the honorable imperial consort, basking in unwavering favor.

Emperor Xuan Wu: At first, it was lust at first sight, but later I became truly captivated by her charms. Who knew this woman had so many more faces that I was unaware of?

Jiang Xinyu: The emperor is the harem’s highest-level boss with the thickest health bar. If I can deplete his health bar, I can become the supreme empress of this harem.

P.S. The heroine is solely focused on her career, yearning for riches and glory, a life of luxury and indulgence. She excels in all pursuits, with layer upon layer of schemes to conquer the emperor’s heart.