I really love your games, Nami. I will say though this one left me wanting for a bit more, and not really in an entirely positive way.
Spoilers ahead in case you haven't played the game:
I felt like Maia's conflict was under-explored and felt like it came suddenly. Her earlier actions (or possible inaction's) being accompanied with relatively little dialogue, and not much facial expression. Even something like allowing her to ignore Am when she's stuck or lie to Am and Melite, led me to think she didn't really care actually. I thought she was just going with the flow. Even her simple "Okay" response to Clio felt very curt. So when she leaves the sea for the first time and starts breaking up over leaving her new friends, I was a bit, confused.
Regardless I was excited for the development since it potentially gave a new depth to her character. It seemed serious too, so I was curious to learn more about Maia and her problems! Maia really looks like a character with a history based on the hints she gives to Am when she leaves the first time. Her comment about "surviving up here," is just, very implicative. Then I felt like that never really happened, we find out a bit more of her doubts in the deep sea, but we don't find out why she has them, and considering she was potentially willing to throw her own life away in the depths, I thought that was important.
I feel it may have helped to see a bit more of her internal thoughts, or to explore her feelings and past a bit more through the other characters, who she doesn't really ever open up to? Even when Clio confronts her about the party Maia doesn't talk about herself much.
Finally, I felt there could've been a bit more development between the core 3 characters. Maia and Am never really interact outside Am leading her around a bit, and while Clio does have a couple moments with Maia I didn't feel their relationship really developed. I would've liked to really just see more of them together, maybe another day even. One where they actually just hang out, talk a bit more, maybe they play hide and seek for real in the kelp. I think that alone would've made the payoff a bit weightier.
I hope this isn't too negative, I just genuinely like your work a lot, and even if these were very personal thoughts and not objective facts, I figured I'd share. Looking forward to whatever you make next.