For those that want to see more of Shimamura's perspective, I recommend the LN, while I don't disagree with Shima being "slow" in this manga, in her chapters from the LN she does have an idea of what's going on, but tries to be in denial about it since she has her reservations about her relationship with Adachi growing more and more.
I though this chapter was rather nice, the strengh this adaptaitaoin has for me at least are the funny expressions and a more light hearted tone than the source material, that being said, the number 1 friend scene was funny and all right on its own, but certainly not how I imagine it while reading the novel.
I also hope that both the new maga and the future anime can do it more "justice" boomerang scene and all.