All the trio moments between Clain, Phryne, and Nessa—from Clain comforting Nessa when she fears that she will disappear to the trio simply sitting outside and watching the beautiful scenery together. Especially this scene.
Phryne: Clain... What would you wish to the day star?
Clain: I'd ask it to let me stay with everyone forever... maybe...
Nessa: Then it'll come true because Clain, Nessa, and Phryne will be together fooooreeeeveeeer!