Osananajimi o Ushinatta Natsu...

Their town wasn't big enough to be called a city, but it wasn't too far off.
Tomoki Oosumi was more than happy to help Kanae Shinomiya prep for the local festival. She was shorthanded; her parents had left her to manage the shrine herself. It wasn't the first time, and it certainly wasn't a bother to Tomoki. Any excuse to hang out with her.

He arrived and started cleaning when Shinya Kaidou came around.
Shinya was the closest thing Tomoki had to a love rival. Hot-heated and quick to violence, Shinya never gave up trying to "get" Kanae
while only giving her more reasons to dislike him. Kanae knew aikido from her father, and today she used it on him.
Shinya was humiliated.

That night, a spot behind the shrine was vandalized.
Kanae didn't know the origin of this "hokura" or who broke it, but soon enough she heard rumors of demonic sightings and assaults around town.
At the same time Tomoki noticed a change in Kanae.
Shinya was no longer coming around like before.
At night, he was having disturbing dreams......

Something terrible was unleashed when that hokura was broken------

[From DLsite English]