[Otus]

Originally Posted by Molenir

I've read the translated version of the first 4 novels, maybe I'm getting it from there. I just have this vision in my head about Yuuki being nervous about being alone with Kashiwagi, at the sleepover, and hearing about the reason why. Is that really from the novels and not from the anime? Don't have time at the moment to go back and rewatch them.

Yes, that's all in the novel I'm afraid

Spoiler for Season 2, Episode 1:

In the anime, Yuuki plays no part other than him simply being there. Before going to bed, Yumi starts wondering if Yuuki has already gone to sleep and Sei makes a joke about Yuuki being in danger. It's quite clear that Yumi has no idea what she means by that, which is most likely, because she's unaware of Kashiwagi's preferences.