The supporting character's harem is very normal - Chapter 461 Karol Magic Academy.

Crying blood and tears, she pledged a poisonous vow. The gods did not fail her. She was sent back to a decade ago. The legitimate daughter of Jiang family returned from hell.

Forget it, whatever! Since they already claimed that she was a temptress that wrecked the country, she shall overturn the world into complete chaos starting with her beguiling sister, her malicious stepmother, her cruel lover and her heartless family. Let her end the lives that Yama refused to end.

She was a pawn in her past life. In this life, however, the world was her chess board. With an alluring smile and a charming figure that enchanted the entire nation, the red-clothed woman wrecked chaos among the lands. She was a vengeful spirit from hell, determined to make those who wronged her pay in blood.

“I want those who owe me a life debt to hold their hearts out in front of me. I want those who looked down on me to only be able to admire me. I want Lord Zhong Zi to shiver when he sees me. I want to step on this splendid river and mountains!”

— — —

“You are a temptress and I am a thief.” His robe was as dark as the night and his gaze was as cold as the Northern Star. “A perfect match.”

Her red dress was akin to fire, but her heart was the coldest ice in the winter.

He was stoic in his black robe, yet he was willing to warm her frozen heart.

In this life, the elegant man seemed like a snowy bamboo grove with tall, chilly mountains, walking step by step towards her like an unstoppable force.

“Ruan Ruan, if you hate the world, then I shall conquer the lands with you.”

“What if I love the world?” She asked.

“I am the world, so you can only love me,” he answered.

- Description from Novelupdates

After possessing the game’s villain, my goal was solely one thing –

To escape from this cursed game world.

[Embrace a death befitting a villain]

I failed on the first run.

But I resolved once more to escape this world…

“I missed you, Kyle.”

Yet the heroines who once loathed me began to plead for my affection.

She is someone with the nickname “Seatmate Killer”, and also one of the prettiest girl in the school. Every male student that became her seatmate has confessed to her, and all of them got rejected brutally. The one who became her new seatmate, the seat beings located the furthest away from the front and beside one of the windows, thus being a godly seat that will make every male student jealous, is Narito Yuki. He is someone that generally you won’t notice at all. The entire class thought that he will fall for her in a short time, but that may not be the case…..

Our straight (?) bottom woke up ten years into the future and found himself on the bed of his childhood friend… At the start, the bottom was shocked to his very bones, but he soon quickly accepted this premise and found the whole situation to be rather amusing. Precisely then, the bottom once again went back to his timeline — back to when he and the top were just platonic childhood friends.