here it is!! ヾ(❀╹◡╹)ノ~
https://booktoki465.com/novel/1822593
Kim Shin is always looking out for Hajin, sometimes even too much... he clearly likes Hajin too so Choi Seonwoo is extremely jealous of their friendship. Kim Shin never gets out of the friendzone though, so I don't know if you would call it a good ending but it's not like he had a bad ending either haha
I read on booktoki in korean https://booktoki465.com/novel/1822593
Hi guys this is the novel updates page
Manga seems ahead rn
https://www.novelupdates.com/series/yes-its-me-sub-yandere/

Just finished the novel!! I enjoyed it but I felt like the ending was too rushed. Also around half way in I had completely forgotten that this was a transmigration novel because the author never mentioned it again and it isn't useful to know what the original webtoon is about apparently bc its completely different, so it kinda looks like they just dropped that tag lmao...
Both the novel and the webtoon are r15, there are just some very steamy kisses and it is very implied what they do, it felt like they were teasing me. It will be quite a long webtoon maybe 3-4 seasons but I think its worth to read it, it's actually fun and with some cool plot twists.
I scrolled through some comments to see what people were asking so here are some answers: there is no side couple, there is no love triangle. Hajin (black hair) is bottom and Seonwoo (brown hair) is top, the opposite of the og webtoon. It's kinda a harem as in almost all male characters (main and side) are attracted to Hajin, yes the og main character (Shin Yeonwoo) appears and he likes Hajin too. And yes happy ending for mcs and for all the ones that deserve it. The transmigration thing is never touched again so I'm guessing he just stays inside the webtoon?? Let me know if you want me to answer to anything else.
My korean is decent so I read it in korean on booktoki, I looked it up and there doesn't seem to be an official or fanmade english translation, sorry :(