The supporting character's harem is very normal - Chapter 285 Alec’s arrogance

A useless prince, yet brimming with kindness and compassion—his smile as warm as sunlight, illuminating this darkened era.But that was merely a mask, hiding the poisonous and mad nature beneath.A monster lurking behind a gentle shell.A system that feeds on stolen Heroines.He will outplay destiny—and rise as the world’s ultimate villain.

Monsters cover the sky, and false gods sit high in temples.Qin An crosses into this world and awakens life skill professions.[Butcher: Mastery of Blade Techniques][Scholar: Enhanced Comprehension][Blacksmith: Strength that Can Subdue Dragons]...These life skill professions become the foundation for his survival in this demonic world.

This novel is also known as Only I Level Up

10 years ago, after “the Gate” that connected the real world with the monster world opened, some of the ordinary, everyday people received the power to hunt monsters within the Gate. They are known as “Hunters”.

However, not all Hunters are powerful. My name is Sung Jin-Woo, an E-rank Hunter. I’m someone who has to risk his life in the lowliest of catacombs, the “World’s Weakest”.

Having no skills whatsoever to display, I barely earned the required money by fighting in low-leveled catacombs… at least until I found a hidden catacomb with the hardest difficulty within the D-rank catacombs!

In the end, as I was accepting death, I suddenly received a strange power, a quest log that only I could see, a secret to leveling up that only I know about! If I trained in accordance with my quests and hunted monsters, my level would rise.

Changing from the weakest Hunter to the strongest S-rank Hunter!

- Description from Novelupdates

Zhou Donghuang, a man from the Earth, is able to destroy any planet in the universe without lifting a finger. His supreme will can sweep across the vast cosmos in the blink of an eye. And his immortal spirit can depart from his body and wander around the universe!

In Kunlun Mountains lies a circular slate, which brought him back to one thousand years ago…

- Description from Novelupdates