It's hard to get views when starting a novel so I hope that this will help.
Title: World-Class Psychopath
https://m.webnovel.com/book/14618588805964405
Genres: School Life, Romance, Action
This is about a popular student named Cress who survived a horrible school shooting which almost half of the students died with few of their limbs intact. At the same day, he received a letter from the school shooter as she massacred his classmates unhesitatingly.
But unexpectedly, he was invited back to school, Mun Academy, the day after.
On his arrival to the school, there is only strange one room left and no students elsewhere. There, he saw a wide range of strange people, from a princess to an otaku, from a military soldier to a martial artist, from a suicidal to a school shooter!
From there, Cress was about to enter a world hidden beneath and above the mundane world while learning the existence of [Abnormals]