"Just you watch, Sea God! We'll put on a ceremony that not even you can ignore!"
Feelings and change can be a difficult thing, and NagiAsu sure as hell shows that incredibly well. While I'm not sure when and why I originally decided to put it on my "want to watch" list, I really don't regret it.
While the story may look simple on the surface, the characters are incredibly well portrayed. And while I can't say for certain how realistic they are portrayed, they put a lot of attention in the relations between the characters, both the main characters and side characters. This made it easy (or easier, given how complicated emotions can be) to understand how characters were feeling, whether you agree with it or not. The change of the characters feel natural (and to me logical) too.
The entire anime is also visually super appealing, and makes me question if the more modern visuals lack the personality older anime (like NagiUsa) have. The attention to detail is great, whether it's the underwater city, or the surface town. Nothing looks bland, but I never got the feeling anything was overdetailed either, pretty much everything felt just right. Of course, the music is also great and really compliments the scenes in every good way possible, emotional when it needs to be, silent when it fits, etc.
I'm quite an emotional wreck when it comes to sad and happy things. This show was an emotional rollercoaster in the best way possible. And besides that, NagiUsa also is clear in the message it wants to convey (or at least, what I picked up from it!)