Can anyone remind me who's Jae-Hee again?

No I don't know sorry

It's alright sweets ლ(´ڡ`ლ)

I think hes mc's little bro

MC's brother's name is jongwoon (or something like that) I got confused at first too, Minyoung is talking to this Jae-Hee guy about MC's brother and wether he killed him or not

I think he is Cheol's stalker that we briefly see in the flashback arc ?
Cheol saved him once and the guy has been obsessed with him since then. He tried breaking Cheol and Minyoung apart, in school. No matter what Minyoung tried (mine blackmailing hum with his dad's affair) he couldn't make him stop following Cheol. After Minyoung and Cheol broke up, Minyoung ended up making a deal with the stalker, he sent him photos of Cheol while he was stalking him for years, but now that Minyoung is back with Cheol and doesn't need him anymore he seems back to cause troubles