What even is happening? So lost, who is kwon minjae?

this is actually a sequel for side characters from the author’s other work. Kwon min jae is the black haired crush in the past.

Min jae had sex and become boyfriend of black haired dude, Damon or Jin woo' s brother now

Ohhh I see
So do I have to read that story first?

If you want, just do it. However, I think it's okay if you read this carefully since both Damon and Colty didnt show up much in the prequel