He is Seok kang from questism which is a spinoff of lookism. If you wanna know what the plot is it's about a bullied boy named suhyeon Kim. One day he was given a quest window which allows him to do quest to get stronger. His then forced to become the leader of west gangbuk to reunite gangbuk after the legend of gangbuk disappeared. If you wanna know more about the legend of gangbuk his name is Johan seong and he is from lookism(he isn't the mc tho).
If you like it their are other manwhas connected to all of them called ptj verse.
The manwhas:lookism,questism,my life as a loser, how to fight,manager Kim, juvenile law. The strongest ptj verse manwhas are lookism and manager kim