Residential areas, farmland, and mountains in the distance. It's not a remote area, but it's not a city either. It's not a city at all, but it's a country town.

The protagonist returns there at the height of summer and takes a job as a temporary live-in janitor during the summer vacation at his old school.

There, he finds his cousin, Otowa Takanashi, who moved here after her parents' divorce, and his old childhood friend, Rino Akatsuki.

Otoha was taking supplementary classes for new students, and Rino was attending school during the summer vacation for club activities.

The girls used to be familiar faces who would play together when they were younger.

The relationship between the three of them was not the same as before, but had changed slightly.

Is it because they have simply grown up, or...?

The protagonist suddenly starts to get involved in a special relationship with Otowa and Rino.

"Where the events that take place in a locked room in midsummer are headed..."