This volume deals with Asaba (Naoyuki) and Iriya's first date (probably mutual) and "kyokujitsusai," which is kind of like bunkasai, but stranger.
Their first date is told using multiple points of view. The most prominent one is Asaba Yuuko's point of view. Anime had almost none of that. Kyokujitsusai story also has other interesting points of view, such as that of Asaba's parents' and that of Akiho's. I always wondered about how Akiho managed to get alcohol during the festival, but that's also explained in the novel. The whole kyokujitsusai has many sides to it, some official and many not. That underground "tea house" was one of those unofficial things.
Akiho's first meeting with Asaba is also described in detail. I couldn't really understand that scene in the anime, with Kiyomi crying, teacher yelling, and Asaba defending, but now I do. Akiho is such an interesting character. I hope she and Asaba get along in the future.
There is also an extra chapter detailing a particular secret that supposedly has something to do with Area Sonohara. It's told through secondary, and tertiary characters, so it's extra mysterious. A person with a particular experience happens to tell a girl, then she tells her friend about it over the phone, and something happens to the first girl... probably. There are two lessons here. 1) Don't ever say strange stuff over the phone. 2) If you do hear it, act like you don't believe it, at least over the phone, or anywhere you may be bugged. Oh, crap. They're gonna come for me. I better wipe my website from my HDDs.