95% sure it isn't. I'm currently up to chapter 254 of the novel and there hasn't been any 18+ scenes yet. The novel is still being released so maybe it could go in that direction, but I doubt it. I saw on a Korean site that it was rated 15+.
do they kiss much?
Kinda. The romance is pretty slow at first, then there's a couple kisses here and there, and then sometimes they really go at it (not 18+).
Thanks for info! I was worried it could be only bl coded like “s class that I raised” but good that they at least get touchy with each other
Is novel +18?