My only gripe with this manga is that we don't see enough of Ashita's side of the story until the final acts. She was just as, if not more, wracked with regret over the relationship ending. I can't tell if Ashita's ability to remain in good spirits until the final act is bad writing or really good writing... On the one hand, she seems kinda detached from reality whenever she's around Kyouichi. On the other hand, she might be able to remain composed because she unconsciously knows that it's all gonna work out in the end... since she literally wrote how everything would happen 10 years before the events transpired.
@MCX01 and
@Rice
The concept of the UFO retroactively makes sense because it's a physical manifestation of Ashita and Kyouichi's regrets and desires.
The UFO only appeared because Ashita was so wracked with guilt while writing her story "Ashita Dorobou."
Was the UFO under-utilized? Definitely, but it made sense as a plot device.
She willed her story into existence.