i lost the plot lmao can anyone recap why is he getting revenge?

From what I remember when Yohan was younger (like college age) he was dating Myungshin (trifling guy with the light brown hair) and Myugnshin did something that caused Yohan’s younger brother to get murdered. So basically Yohan wants to get revenge for his little brothers death by infiltrating the entertainment industry where Myungshin is trying to succeed and ruin his life . I hope this made sense :(

Myungshin directed a vengeful loan victim that yohan pressured previously. The guy lost everything and was planning to stab yohan. He met myungshin, threatened him too, and myungshin told him that you should stab his brother to make him feel the same pain. So the guy stabbed the kid. And died cos no one was there to help. Myungshin escaped with all of yohan’s money. Then years later, uphan pverheard myungshin boasting and gloating at what he did, at the money, and belittled yohan and his brother.