Haruka and Yuu's first kiss, a way to keep their friendship special.
Shizuku and Kotone's first kiss is preceded by Kotone telling Shizuku that while she likes living at her house for convenience, Shizuku herself is what makes living there the best.
Kaede became Class Rep in every grade except one because Yuzu fell and got hurt when she was Class Rep in grade school and Kaede didn't want to see it happen again.
Shizuku and Kotone's second kiss comes after Shizuku saying that being with Kotone is the reason she's sleeping over at the school with the group because being with Kotone makes everything better.
There is also a bit of a retcon from episode one, what at first seemed like it was just Kotone teasing Shizuku about her name turns out to be Kotone's way of helping Shizuku make friends.
Haruka and Yuu reconciling in episode 8. The best part is that they weren't avoiding each other out of anger but because their UST had become too much.
Kaede crying because Mitsuki and Rina were graduating, because she is part of the student council she had gotten very close to both of them, which reveals that she gets very attached to the people in her life. Then hiding her face in Yuzu's back prompting Yuzu to take her away to help her cheer up.
Chapter 43, as everyone is making posters for the cultural festival, Kotone is reminded of a painting class she had with a strict teacher, and feels like her work is another class project — she can't help but judge it as her teacher might. So, Shizuku puts paint splatters on it — even though the professional quality of the work is lowered, it becomes something they can remember having fun working on together.