This starts with both the introduction of Ai Kamiya & how Shikimori & Yuu started dating. For Kamiya on the surface she appears similar to Nekozaki but rather has a cute side hidden in her. Which is an interesting contrast to Shikimori who on the surface seems cute but has a hidden tomboy side in her.
The scene between Kamiya & Shikimori is nice because it shows some of Yuu’s tendencies rub off on her. More so the point of understanding what someone is truly feeling. As both Yuu & Shikimori are dating, there really isn’t any way for Kamiya to express her feelings without coming across as a jerk. So here Shikimori offers Kamiya a shoulder because just because they have feelings for the same guy doesn’t mean they need to be hostile. Kamiya’s feelings are as real as hers. Kamiya respecting their relationship means that Shikimori must respect the feelings that Kamiya holds as well. Hopefully it starts a friendship between these two.
Even coming from that, it’s good that Shikimori still prioritizes her own feelings. That’s good to see. Now we start to see Shikimori express her interests, as with the aquarium date. Which shows their relationship is in a healthy spot.
The bonus chapter showing how Nekozaki & Shikimori became friends was very nice. While the two are polar opposites on the surface, Shikimori is quite similar to Nekozaki inside.