[Kazu-kun]

No episode 5 thread yet? I just saw the episode and it pretty much confirms our theories about sex.

Spoiler for episode 5:

Saki and Satoru got separated from the group, and they almost have sex. It was just a whim. They were alone and Satoru wanted to do it, that's all.

The only reason Saki didn't went along with it is that she remembered what the library said about the bonobos, and she stopped to prove to herself that she isn't a monkey. She explicitly states, in her thoughts, "I'm not a monkey".