The only thing that makes this anime worth watching are the scenes in which the piano is being played.
The integration of the music and the character's feelings is very well done, and the animation for the piano keys being played was truly incredible to see.

Unfortunately, the good parts stop there, because the rest is an amalgamation of tropes and sob stories.
The worst part that truly left a mark on me was how tropey the main girl was (indeed, I do not care enough to check her name again): we are introduced to her dancing barefoot in the flowery spring, on top of a children playground, naturally playing a likewise quirky child-like instrument. God isn't this girl the sweetest, liveliest, most lightweight girl of them all. And we, the audience are constantly reminded of her quirky over-positive energy, just in case we forget the miracle of existence of such a pure and angelic being in this wretched universe. Evidently, this girl is there so the audience can feel something when

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she suffers the most unfortunate fate, that of an incurable illness

.
In short, the purpose of this character is

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to die, which makes it frustratingly predictable very early on in the show.

Admittedly, the other characters were a bit better, but also not far off from the group that just works too well in overly dramatized story-lines:

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the depressed boy in need of salvation through romantic love, the adorably dumb jocky friend, and the side chick with unrequested love for our depressed boi. And of course, most importantly of all, the angelic deity that comes onto this Earth with the purpose of blessing our depressed boy and dying in the most stoic and dignified manner (any other way of dying would be unthinkable for this divine creature)

All in all, it was a jog to get through, and most of the episodes are only bearable because of the brilliant specs here and there of when they actually play music. Also, there is indeed some credit to the plot of the relationship between

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our depressed boy and his mom. I found his mommy issues quite intriguing and the slow reveal of why his mom was such a bitch very engaging and interesting.

Some of the side characters are better than the main character, and I found the portrayal of the music career very engaging. It really is a shame they didn't have such a tragic past so this show could be centered around them instead.

In conclusion, it is obvious why most people like it: the divine entity in this show suffers a most unfair fate (very much like Jesus, except his voice was probably less annoying and he didn't look like the clown emoji), which makes us grieve, and agonize, and to come back for more.