Powerful MC's

After being accused of murdering a colleague, Cassian Lee came to his death. The moment he thought it was all over, his soul was suddenly possessed by a boy’s body and he awakens as a villain.

Kim GiGyu awakened as a player at the age of 18. He thought his life was on the track to success, climbing 'the tower' and closing 'the gates'... But even after clearing the tutorial, he was level 1. He killed a goblin a day, and he was still level 1. Even after 5 years, he was still level 1. "Who would have thought that this kind of player would exist." No one knew.

MC is a super popular guy in college, but he hides a pair of insect wings that he's super insecure about. He got them after using a mysterious substance called "jungle Juice". One day, he reveals his wings to the world when he saves someone dear to him. When all hope seems lost, he suddenly stumbles upon a secret society with people just like him - but in this world, only the strongest survive.

Na Hwa-jin, a member of the Education Protection Bureau, begins 'true education' to protect the collapsed school authority!
Mc basically goes around different schools with either corrupt teachers or corrupt students and gets them back on their feet.

Chung Myung, The 13th Disciple of the Great Flowery Mountain Sect, One of the 3 Great Swordsmen, Plum Blossom Sword Saint, defeated Chun Ma, who has brought destruction and disarray onto the world. After the battle, he breathes his last breath on top of the headquarter mountain of the Devil’s Worship Sect. He is reborn after 100 years in the body of a child. ……What? The Flowery Mountain Sect has fallen? What kind of nonsense is that!?

MC is the demon king and Prince Lagier from Jerlayla manages to summon him. Lagier is an evil and fat guy who seeks world domination, however he ends up dying the moment he summons the MC. MC takes over Prince Lagier's body and needs to fulfill Lagier's wishes before he's allowed to leave. But first... he's decided to lose some weight.

"Please don't touch the guy wearing glasses…" Department head Kim, who quit his job as a special agent only for his daughter Minji and chose to be normal. Then one day, Minji disappeared silently, and Manager Kim began to find his daughter by turning the country that monitors him into the enemy.

A writer who has failed national exams is recruited by a martial arts master and tasked with recording his life in a book. Through their journey, Son Bin meets many great people and soon finds himself on the same path as the master, to become the king of martial arts.
Unfortunately, there is kind of a harem here, but most of the women aren't unbearable and don't senselessly make trouble, so it should be okay.

MC is an F-rank hunter with a younger brother who awakened as one of the first S-ranks when dungeons started breaking out. After his brother awakened, he started distancing himself from the MC, breaking off ties almost completely. MC feels like he's been left behind and does anything to catch up with his brother, failing in the end. But then he gets a chance to turn back time...