This game is super cute, and I think the concept is great. However, I don't find myself having as much fun playing it as I thought I would. I think part of the problem is that there is a mismatch between jump height/length and the actual placement of many of the platforms. Not that every jump should be comfortable, but it just doesn't feel good to have to slow down too much to fit in extra jumps.
Another potential improvement could perhaps be to also have the option of reverting Suwako's position when the coins are respawned, so that the player can retry the same stage route straight away.
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Edit: I take back what I said. The game is great, period. Previously, I hadn't realized that it was possibly to jump out of the dive landing by buffering inputs, and I might also have needed some time to digest the levels and figure out how to make certain jumps.
New suggestions for improvement would be to make it possible to jump out of the dive landing by pressing jump while on the ground, since I didn't even realize it was possible before consulting the game page.
It's also possible to get semi-stuck against walls mid air, and also against the roof of the shrine. I also think I managed to soft lock the game by getting stuck against a wall like this while under water. Also, I believe new scores for a level overwrites the previous score, even if the new score is lower (for example, completing a stage with bronze rank will overwrite any previous rank, even if they are higher).
Even with these annoyances, the game is great, not just as a jam game but in general. I just got all diamonds.