
I think it's because it's the beginning and the updates are not regular (no complains here, I'm very thankful to be able to read a translated version :) ) so we kind of tend to forget the details in the story.
But the flashback we saw in ch3 was actually there to explain the moment where the uke (Kei) recognizes the seme (Mei) in ch1.
So in short : Kei is bad at gambling, tries to play anyway and got indebted to guy number 1. Guy number 1 asks for payement (which Kei doesn't have) and tries to rape him. Mei saves Kei and asks for repayment for the game Kei lost against him and for the fact that he saved him. Of course, the uke doesn't have money so he sells himself to Mei.
And now we got some explanations about how they knew each other as classmates before and why both of them remember the other.
ヾ(❀╹◡╹)ノ~
The story is kind off bruh I don’t know like I like the main character but the story doesn’t really make sense maybe I’m the only one idk