I think it might be enough saying that the dark haired girl (Gyerin) had some feelings for the female main character of Sadistic Beauty but the main there saw Gyerin more like a friend + benefits.
Sadistic Beauty is not bad but at some point the story took a turn that left many perplexed Oo. There were many depicted situations that looked forced or out of place.
If u look at sadistic beauty's uploading dates you'll see it got dropped in 2018 and picked up last year. It only goes to shit on the 2020 chapters, and the MC (Gyerin) of this story only appears in the 2018 chapters anyway, so that may work for you.
Wait no just checked back on that there's a few rape chapters at the end of 2018 lmao. You should read maybe up to chapter 43 if you decide to read it (and you can also read chapters 61-64 mentioned in the translators notes, it's just some nice rpleplay between them.)
But yeah, overall it has nothing to do with Sadistic beauty and as long as you know she had an unrequited love with Sadistic Beauty's MC you should be good.
And maybe adding that cute Gyerin has masochistic tendencies. (=・ω・=) She's so sexy too. (●'◡'●)ﾉ
Can i read this without reading the main story cause i heard that its bad.