
It's not a spin off, although there are connections between both stories: same universe, some characters appear in both, they share some events.
As for the novels you can read them on their own, since they even belong to different series of the author. As for the manhwa adaption it depends on how much they leave out, but even so you can read it without reading KML.
And if you don't like stories like KML, I wouldn't read it. There are a lot of readers who don't like KML, but like this story.

I actually ended up reading KML( ̄∇ ̄"). I had to push through the first half but completed the side stories and feel the best take away was Spence being a cute kid and Keith being a mid teir example of character development. I also caught up on kiss me if you can and can agree that KML info so far is not crucial. Thank you all for the help!

yeah but readers don’t read the author’s outline, we read what came out first. KML dropped first, it introduced the universe, so that makes it the main anchor whether the author planned more or not. the other novels shift focus onto different characters, that’s literally a spin-off. sure, a spin off has to branch out from a main story, but by release order, KML serves as the main story whether or not it was the author's first idea, as it introduced the universe. it’s the same way harry potter came first and set up the wizarding world lore, so even though fantastic beasts is technically a prequel, it’s still a spin-off because it branches off with new characters and stories in that same universe.
Help! i understand this is the spin off couple from kiss me liar. i wanted to know if it can be read as a stand alone or if i have to read the other story first.
thanks!