Weak to S.T.R.O.N.G

Kai doesn't have family anymore and is training at beavenly sky pavilion. At first he is weak and everyone chalenges him to duel. Also he has strong will to never give up. One day he gets book in which is writen how to train and quiqlier become strong

MC is nerd and does not care about anything. After his parents and sister dies he starts living at other place and decides to kill himself. He looks weak but after monsters starts to appear he does not have a choise but to change and even try to save others

Well then becouse of him his sister died he reincarnated again and changed himself to good and strong person.

Lee SungHoon, in need of money because of his mother’s sickness, takes a dangerous job to help hunt those monsters four times a month by acting as a bait for the hunters But one day, he is heavily injured by a monster and remembers his past life as a sorcerer king ‘Huh? Did I just die?» ‘Wait, I was a Sorcerer King Kratraus in my previous life?’ With his past memories, SungHoon’s overpowered magic show begins.

In his original world he was considered wortless. He had support his family, so he was ready to sell his soul if it means to find a job. And when he clicked the ad, MC started to work in other world as a replacement for clients. He had to do bad things even kill people, but for his family, MC did everything company gave him.

By using the trash jobs that no one pays any attention to, with the right attitude you're bound to accomplish your goals! even succeeding at the most impossible of quests, the main character bets everything he has. "With my skills I'll beat this game!"
This manga is really interesting and funny, becouse MC invests everything in luck, well ordinary people woudn't do that, but being chalenged by strangest things is the best...

He was just unemployed man, but after he knew that he can revive multiple times, MC starts fighting for one student girl and he himself changes dramatically.