The supporting character's harem is very normal - Chapter 32 Blood Frenzy

Going against the heavens, Tuoba Ye reincarnated. Body concealing Divine Root, hands holding Divine Talisman, possessing previous life’s experiences, from childhood, began cultivating the most difficult body refining method: Mythical Nine Transformations.

- Description from Novelupdates

Cheng Yujin was the elder twin sister, who was supposed to be engaged to an excellent man. However she later learned that her fiance, Marquis Jingyong, had proposed to her because he mistakenly recognized her as her younger twin sister. Marquis Jingyong and her younger sister had a deep relationship, and after many twists and turns, finally broke through all hardships and became eternal lovers. While Cheng Yujin was the villain who replaced her sister’s good marriage, kept framing her sister, and hindered the main couple to be together. A really wicked older sister and poisonous ex-wife.

After the younger twin sister was reborn, she revealed Cheng Yujin’s ‘conspiracy’ early on. Everyone scorned her, and her so-called fiance was indifferent. Cheng Yujin sneered and tore off their engagement letter in front of her fiance.

Everyone was gloating and happily waiting to see her regret her actions. However, before Marquis Jingyong had a chance to see Cheng Yujin’s regret, he saw his former fiancee marrying her uncle.

The ninth uncle of Cheng family was truly a hidden dragon, his real power frightening everyone.

***

Cheng Yujin, this coquettish little wife, lightly lifted her eyebrows and casually said, “A mere Marquis Jingyong, is he worthy? Do you think that robbing him away will affect me?”

Almost forgot to say, ninth uncle wasn’t surnamed Cheng. His real name was Li Chengjing, the crown prince.

There was a woman. Born as an illegitimate child and raised under the strict control of the queen, her world was as small as a well.

There was a man. He was forced to marry a woman who was his brother’s political marriage partner. His world, which was infinitely wide, became smaller.

The woman’s original sin, and the man’s resentment. “I should have just died instead…”

With the Goddess’ blessing, he became a 『Divine Knight』 and founded an Empire.
As time passed, he grows older, and by the time the heavens called for him to come, the Goddess showed before him, asking for his last wish.

He wished to be reincarnated in the future.
He dedicated all his life for his people, he had no time to master his own arts.
This time, he wishes to live for himself, forging his body to the utmost limit.

The Goddess complied with his wish.
In the far future, the King shall reincarnate as the 『daughter』 of a renowned Knight family.
And, under some circumstances, she is labeled as a failure of a Knight, however——

「How convenient. I can stand on the foremost line without needing any rank. No better training than actual combat!」

Thus, the legend of the world’s strongest, most beautiful Knight Disciple (♀) has begun—