You're not gonna like my answer. I'd suggest reading from chapter 1. Seriously. A lot has been left out in the manwha and tho I understand the choices, readers miss out on the inner monologues the characters have and it's such a shame. I seriously don't think this is one of those you can jump into the novel when you start off the manhwa. Then again, I could be wrong. Just stating my opinion.
I've also read the novel and I agree with you. Start from c1
If you're reading the rubymaybetranslations id say Book 4 chapter 50 is a good place
hii guys! so i want to resd the novel but dont know which chapter to start with if i ended on chapter 115 in the manhwa...please help *dogeza*