The supporting character's harem is very normal - Chapter 520: Arine and you?

Natasha Novak was a fairly known artist from an Earth devastated by pandemics. One day, she was playing an online game and falls off her chair as a moment of luck brightens her otherwise monotonous life, and dies of a stroke due to hitting her head.Reborn in Galeia, a world of magic, she sets out to explore this brand new planet and maybe find others like her. Join her and her companions as she faces a world with a culture alien to her, meets Gods, and takes part in adventures all over the globe.

“Each betrayal leaves a scar… and hers ran the deepest.”Once, Aveline Laurent gave her heart to Damien Ashford - the man who promised her a future, only to cage her with sweet lies.She endured it all with a smile… until fate dragged her back to the very beginning.Now, with a second chance hanging by a fragile thread, Aveline returns.Not to plead, but to punish.
Not to forget, but to make him remember.But revenge is never simple. The path is fraught with shadows—and an unlikely ally–Alaric Lancaster–whose loyalties remain as mysterious as his gaze.

She had a lifetime of fake virtue without receiving a virtuous ending. In the next lifetime, she controls fates with the flip of her hand. To the jerk who wasn’t faithful, she’ll draw a premature death talisman for him. For the poisonous step mother, she’ll send a death flower. For the step sister who is two faced, she’ll personally rip off that fake pretty face!

But when she personally offered up her body to her nemesis because of a child who she had no fate with, something unexpected happened. The night of the big wedding, the groom changed and a cold and luxurious man pushed her down. “You can marry whoever you like, but you can only give birth to my children!”

- Description from Novelupdates

Cyril was a Harry Potter book fan. He unexpectedly obtained a chatterbox system that said it would take him to experience the desired Wizarding World.

He rubbed his hands together gleefully. Was there such a good thing?

However, once the system was finished, he found that this Wizarding World didn’t seem quite right?

Cyril (eyes shaking: Forest monster? Brass steam train? Gloomy wizard’s tower? Wizarding academy of the fittest? This wasn’t right!

System (forcing itself to be calm): Magic creatures! The appearance doesn’t matter! The architecture isn’t the key! It is still a wizarding academy! There isn’t anything wrong with it! Not bad, not bad!

Cyril struggled to make it through the Blackheart Wizard Academy. Fortunately, there was the gentle and courteous chief gentleman to cling to. This was until he found that the handsome chief seemed to be plotting against him…

My god! This seemed to the other identity of the crazy great magician and necromancer?

***

According to legends, the dark, paranoid, crazy and perverted great necromancer rubbed the white and delicate neck of the beautiful young man in his arms and whispered, “My dear, I heard that you have been very close to the commander of the Holy Light Knights recently?

Cyril denied it three consecutive times with an innocent face, “I’m not! I didn’t! Who is talking nonsense?”

- Description from Novelupdates