It's a highschool regression story; we start with a 30ish yr old MC, who became extremely introverted during her school years and have just wasted away in the years following. She has a realisation that her parents are very old and she will one day be alone, so she resolves to try and become a functional adult before it's too late. Spoiler, but not; she gets hit by traffic and dies. This is where the actual story starts; she returns to the start of highschool, the time period where she gradually cut herself off from human contact and resolves to make it better this time. Okay, up to thispoint it seemed good. The story was well written and paced, the art is stylised and consistent; all good.
The most bizarre, contrived part of this is that she is now a very "mature" teenager; able to articulate her thoughts and process emotions extremely well. Where did this sudden ability come from?
That's the problem; she spent over a decade completely cut off from human contact since highschool, demonstrated a total inability to communicate with people and no idea how to function in society; suddenly, because the story needs it, she can do all this stuff extremely well out of nowhere.
Cliches start piling up and various male and female characters all start vying for her affections, even though her actions and contribution to their lives are extremely minor favours; it really makes no sesne.
OTOH the characters are pretty well written, they have quirks of their own and don't feel too odd or forced other than the above.
I'm not sure what to make of it; it's a decently entertaining read, but it just can't explain itself internally, and the MC's sudden enlightenment after death is just very out of place.