It's quite a challenging text, I think. The first episode invited me to dismiss it as generic anime fluff, mind you. It looked like another slice-of-life show with schoolgirl friends and a mild SF/fantasy element, but in fact its themes are spiky and resistant to simplistic analysis. (I'm starting to get annoyed with the level of intellectual analysis in anime fandom, by the way.)
Nonoka has returned with her father to a town they used to live in seven years ago. They left fairly abruptly due to Nonoka's mother's illness, but the lady has since died. Nonoka doesn't remember, but she used to have four friends here (Yuzuki, Koharu, Shione, Souta), plus a mysterious blue-haired girl called Noel. Now it seems that Shione's walled off her emotions and is hostile towards potential friends, Yuzuki's turned into an irrational single-issue campaigner and Noel is still eight years old even though everyone else is now fifteen. (No one notices the latter, but in the flashbacks only, she's as big as everyone else.)
Oh, and there's a flying saucer hanging above the town. It's been there for seven years. It's pretty. Yuzuki's been carrying placards for years to persuade the townspeople to get rid of it, although it's unclear what she imagines anyone could do.
That said, it does look like a cute show. It is a cute show. Nonoka is one of those earnest, indestructibly nice anime heroines who'd do anything to help her friends. Nothing terribly urgent happens in most of the episodes. Sunny, shiny, ever-optimistic Noel is adorable. Yuzuki is the kind of goofy attention-deficit idiot who's bad at seeing beyond her immediate obsessions and will do things like accidentally smack her twin brother in the head. She can be funny.
It's about broken promises and the damage this can do. It's about not telling people things. It's about loved ones dying or moving away to a different town. (The line between those two is being blurred, rather oddly, but this makes sense since the distinction can be rather abstract when you're a child.) One of the show's characters is Nonoka's late mother, who might only be a photo on the sideboard but is still a strong presence in Nonoka's thoughts throughout. (In ep.13, we even hear her speak, in a flashback.)
The girls are harsh to each other. Nonoka is brutal to Noel in ep.1. She soon realises her mistake and tries to put it right, but the problem with Noel is that she's very literal and will take you unquestioningly at your word even if she's been waiting to see you again for seven years. Shione probably needs therapy. Yuzuki has latched on to an irrational idea so strongly that her brother tells her she's being crazy, although he hasn't realised what's underneath it.
They're friends. This is all-important. They used to be inseparable, but then they got separated in a needlessly badly handled way. This caused damage.
The show's second half takes a different and less obviously successful tack. Without getting into spoilers, the girls seem to be assuming a lot about what SPOILER might mean. Would it be like bereavement, or merely akin to a friend moving away to a different town? SPOILER seems to be treating it as the latter, but everyone else is reacting as if it's the former. They don't try to think it through, or even discuss it. They just act on their assumptions, to the point of ignoring their friend's explicit wishes. Mind you, the "won't come back" thing is a point in favour of the more extreme interpretations.
Admittedly all this would be more problematic if it weren't at the heart of the story's themes. It's what the story's about. People do this. They react emotionally to that kind of event. Nonetheless all this reduces the power of the apparent break-up, since the whole situation is artificial and we're not fully invested in it.
After that, we then have the last two episodes, in which things get weird. This is the challenging bit. You can't read it straightforwardly as bereavement, or else you'll be forced down some very strange (but less melancholy) paths at the end. Is it just a subjective portrayal of how people react to the loss of a loved one, irrespective of cause? What's going on with the rubber reality? On a literal level, what was that meant to have achieved and in what sense wasn't it just undoing all her hard work? What was the point after that? Why do it? Might it be an attempt to get around the paradox of granting everyone's wish, but then immediately torpedoing it with something that's going to distress everyone? I quite like that idea. Alternative hypothesis: maybe it's an emotional reaction from SPOILER herself, eventually followed by a reassessment of the situation?
Plenty of people have struggled with this show. It looks like cute fluff with schoolgirls. It looks as if it should be light and funny and indeed it basically is. I enjoyed it. However some of these girls have significant problems and their behaviour won't always be friendly or sensible. I found it very interesting.
Besides, it also has the super-cute Noel and a giant flying saucer. You've got to love those, right?