In a small town near the sea called Tokijima the protagonist Ogawa Aoi lives life as she always has.

In the middle of that normal town scenery is a great tower called the 'Tree'.
It suddenly appeared thirty years ago and excited the whole country, but now it is just a deserted tourist spot.

One day, it is decided that the science club Aoi belongs to is going to be closed.
On July 29th, the day before the closure of the science club, all the members go to visit the 'Tree' together.

On that day, at that time, at that moment--
'Tree' starts to sing.
And on July 29th, a loop starts.

[Translated from the official site]