Hi I think I could help answer your question. I read & completed the webtoon first but only watched some of the episodes of the live action so I can’t help you with that. There is no prequel, this is a stand alone webtoon so there’s no novel either. The webtoon contains all the info such as backstory for the characters & settings in more detail. Highly recommend reading it!
As for the live action I dropped it cause I felt it did not stay true to it’s original work which is this webtoon, I suggest you read the webtoon & consider the live action as a loose adaptation since I’m not sure if they added things that weren’t originally in the webtoon, happy reading
that's what always happens with live actions, they change the story line, I only watched a summary of the Netflix series and they were different
So I watched both seasons of the K-Drama before finding out that it was based on this webtoon. I read the first few chapters and both seem different. Is the first season of the k-drama the actual prequel to this webtoon? And even then, does the prequel even faithfully follow the backstory?