
But what about the first chapter of S2 where Taesung confront the mafia guy who hurt Sooyoung and he reveals he killed Sooyoung father or grandfather in the past? Can someone please explain that part because it's clearly the most important one yet no one is talking about it and I don't freaking speak Korean :,((( Did Taesung really killed Sooyoung's relative in tha past and that's why he keeps saying that he knows Sooyoung way before their first official meeting...

There has been some hints about it. And there's actually a scene of a short flashback where Tae-seung shows us how he's been beaten by Soo-young (which is weird because we all know Tae-sung would never let himself get beaten by anyone). By the looks of it, seems that Soo-young is the one who doesn't remember. But yeah they definitely have past. And it wouldn't be weird that Tae-sung killed his father since the father left the debt to Soo-young.
Also, before anyone starts attacking Tae-sung for this too, remember that Soo-young's father was a piece of shit to him too.

Thanks for replying! I thought the beating scene was from chapter 3 (last pages) when Taeseung first kidnaps Sooyoung and asks him to pay his father's debt. When he was beating him, Sooyoung suddenly reacts and gets on top of him and beat the shit out of him with strong punches just like what we see in the flashback you mentioned. Go check it out and you'll see. Also, the mafia guys in S2 tells Taesung that he killed the dad of Sooyoung and he remembers how he was just a teenager with uniform crying... and we do see very briefly a sort of teen with black uniform in Taesung's flashback which I imagines being Sooyoung...
Actually, from the first chapter, Taesung keeps saying that he met Sooyoung somewhere but he cannot remember... and then in the last chapters of S1, he finally remembers and tells to himself that he must protect him and keep him by his side. I was hoping someone else noticed these details and could tell me if I am wrong or right. Because it does not make too much sense. If Taesung killed Sooyoung dad and then comes to ask for the debt to be paid then he surely knows who Sooyoung was...

I will definitely read again. But that aside don't you think that it's weird that Tae-sung killed Soo-young's father when he was a teenager and waited so long to come to Soo-young to demand him to pay his father's debt? There's a missing piece there. I think will have to wait a bit more to know. But yeah, I agree, there's definitely history between them.
THE RAWS ARE BACK! Y'ALL GO SPOIL YOURSELF BECAUSE SEASON TWO IS SAVAGE AS WELL.
spoiler...
Soo-young is whipped for Tae-seung and Minhyuk is acting like a total whore sleeping around and it turns out that he's bi. But it's probably because she's trying to get info from people. Anyways, doesn't change the fact that he slept with that old woman and that old guy.