Romance media usually isn't my cup of tea. There are good ones out there, but the majority of them are either bad or just reuse the same premise over and over again without much in the way of substance. Others try to do new things with it, and some succeed while some don't. Fireworks falls into the latter category, as it tries to do something new with its premise...but really doesn't do it well. Basic plotline is that a young boy, Norimichi, finds a classmate of his, Nazuna, trying to run away. When he sees what happens to her, he wishes to change the outcome, and by way of a magic sphere he finds, he's able to repeat the same day over and over to make it go how he wants to, helping Nazuna in the process. This premise has been done before, but there's so much wrong with Fireworks as a movie. I'm not going to use my usual reviewing style for this one, as I really don't want to waste brainpower trying to make sense of this, so here's a laundry list of the movie's flaws:

1. The main characters are woefully bland, have no chemistry, and there's basically no real reason for them to really be together in any way. Norimichi in particular really can't carry the movie, as he's too passive for his own good, and he just gets dragged into the plot by Nazuna, who's just a mysterious girl without much in the way of actual depth to her. Nazuna also never bothers to consider that she's essentially dragging Norimichi into her scheme and how this might hurt his very clearly loving family who know nothing about her or her issues whatsoever, which makes her come across as very selfish and thoughtless.
2. Norimichi's friends are not only useless, but absolutely annoying as hell, as they contribute absolutely nothing to the movie. Yusuke in particular is especially bad, because his characterization is inconsistent. He asks Nazuna out but then blows her off, but later in the movie, when he sees Nazuna with Norimichi, he completely flips out, which not only makes him a hypocrite, but speaks to the movie's bad writing.
3. There's this stupid, unnecessary subplot involving Norimichi's friends openly sexually harassing their teacher by talking openly about her breasts WHILE IN CLASS, and they don't get punished for it. What purpose does this scene even serve? You could cut it out and nothing would be lost. Seeing that really skeeved me out and there is literally no reason for this scene to be here in the first place, as it accomplishes nothing.
4. It fails to flesh out just why the marble Nazuna has is able to either take them back in time or transport them to parallel worlds, or even explain how this is even possible.
5. The movie thinks it's good at compelling drama and romance when it really isn't, since the two main characters barely know each other and have little reason to be together, but the movies tries to make it seem like they HAVE to be together no matter what by forcing them to be so rather than having their relationship grow organically. Thus, this makes the entire movie feel really contrived and forced.
6. The CGI is awful!! The 2D animation is fine, but there's just so much jarring CGI, from water spewing out of a hose to the characters riding on bikes, and none of it makes any effort to blend seamlessly with the animation.
7. The story is just another rehash of a bunch of other romance media with the exact same premise, only with time travel/world hopping slapped in, and not even in ways that make sense.
8. A good chunk of the movie is wasted on Norimichi's friends trying to figure out whether fireworks are round or flat when they explode, and this also does not contribute to the movie in any way whatsoever, so I honestly have to question why the writers thought padding it out with this was a good idea.
9. The movie is also weirdly obsessed with getting close-ups of Nazuna's and Norimichi's faces and eyes. A lot of the lingering shots on them almost have this...uncomfortable eroticism to it.
10. The premise in and of itself does have potential, but the movie never bothers to use it, just focusing on pointless teenaged shenanigans rather than stuff that actually matters.
11. The ending makes absolutely no sense and comes absolutely out of nowhere, though it's not as mean-spirited as the Ni no Kuni movie's ending.

So, taking all these flaws into account, does the movie actually have anything that's good? For one, the soundtrack is fairly nice, albeit generic and repetitive, and isn't going to blow anyone's minds. Nazuna's backstory is fairly decent as well, but the movie doesn't reveal it until near the very end. Had it revealed it much earlier in the movie, it might have been able to get the audience to actually care about her. Thirdly, the English dub is really good. The kids are voiced by actual kids, who sound pretty good, and Nazuna's voice actress, who is mainly a theater and live-action film actress, does a really good job with her. She's also a great singer, too! Unfortunately, these things cannot save this movie from being an utter trainwreck. Shaft and Akiyuki Shinbo, why did you even bother with this? This movie just isn't good. At all. I honestly wouldn't recommend it to anyone, not even fans of the romance genre, as this is just a rip-off of other, better movies that thinks it can succeed with eclectic animation and weird time travel shenanigans when it just can't.