Volume 2 sticks close to the anime series if you watched it online via crunchyroll. The contract between Kasuga and Nakamura continues, only things get a little complicated since Saeki starts to play a more pivotal role in the series. Saeki and Kasuga go out on a date and begin a relationship all while Kasuga is hiding his secret of the gym uniform from the first volume. Nakamura starts to interact more with Saeki as well playing the role of a potential instigator by telling Kasuga something about Saeki that may turn out to be a lie. In a way, Kasuga starts to develop a second life. His first being the book nerd student at school who is dating Saeki, one of the prettiest girls in school. The second life involves him sneaking around with Nakamura and keeping his secret buried. A secret that plants the seed of an inner struggle.
As the story progresses we can see more and more of the characters dynamics intertwine and how they are starting to develop for the rest of the series. We get more of an insight to the dynamic between Nakamura and Kasuga that begins to show deeper layers than just the contract that was agreed upon that I can only assume will get deeper as the story evolves. The relationship between Kasuga and Saeki is just starting to get underway and should start to be expanded on in future volumes.
Kasuga and Nakamura have their own inner struggles and we catch glimpses of each. Kasuga is torn on what type of person he is and the battle is played out over his choice of which female classmate he wants to be with. Nakamura feels trapped and suffocated in the countryside town the characters live in. This trapped feeling is something that Nakamura feeds to Kasuga and he starts to feel suffocated by the countryside.
The second volume closes on a notable scene with some great artwork. The scene is beautifully animated in the series and plays an interesting dynamic in the future of the story (at least it did in the anime series and assuming the manga and anime continue to parallel one another). The scene is important for more than just the beautiful artwork, in a way it solidifies Nakamura and Kasuga as a unit instead of two individuals.
We get more of an inside glimpse into the characters in volume 2 and each of the characters are becoming deeper, meaning we are allowed to see more of their character and what drives or frustrates them, and the few things that make them happy.