OP School Life (or not)

Yu Ijin was the sole survivor of a plane crash when he was little. After becoming a mercenary to survive for 10 years, he returns to his family in his hometown. He starts going to High school and everything is foreign to him, he also has to protect his sister!

Can he adjust to the new environment and live a normal life?

Once the bullies target you, it’s game over. The school is run by tyrants whose hobby is tormenting the weakest kids in class.

But then Gray arrived.

This mysterious new student threatens to dismantle the established order. He may be small in stature, but his calculative and brutal fighting leaves unsuspecting opponents lying on the floor begging for mercy. Now the school's toughest bullies have to scramble to take down this new and unusual hero.

Gamin Yoon, a 17 year old student, goes to a school known to harbor future criminals.

Stuck in a carnivorous environment where only the strongest survive, he struggles to get good grades to enter a 4 year university. But, will he be able to study well enough to enter university, or will he get involved in the unending fights around the school?

Na Hwa-jin, a member of the Education Protection Bureau, begins 'true education' to protect the collapsed school authority!

(It's more interesting than the summary, I swear)

The journey of Park Hyung Suk and his friends to defeat an organisation while figuring out the secrets behind his beautiful body that suddenly appeared one day and defeating enemies while also trying to keep a big secret.