The Dam Construction Site
The discharge
First Appearance Onikakushi-hen

The Dam Construction Site (also known as the dump, trash heap or junkyard) is an illegal garbage dumping site on the edge of Hinamizawa. It appears repeatedly, beginning early in Onikakushi-hen.

The dump is Ryūgū Rena's favorite place, and she spends much of her time "treasure hunting" in the pile of trash. In the anime, this is also the place where she found her signature nata (also called a cleaver, hatchet or cane knife), which she occasionally uses to free items trapped under the garbage.
Rena also has something of a secret hideout in the dump—an old van deep in the heart of the junkyard, where no sound can escape. She filled the van with things she collected from her various hunting trips and seeks refuge there when she is feeling troubled or sad.

In Tsumihoroboshi-hen, Mamiya Rina follows Rena to her van and attacks her in a fit of anger. In the ensuing struggle, Rena slashes her with a shard of glass and beats her to death with an old pipe. She lures Hōjō Teppei to the dump one night and kills him with her nata in the anime, or a large axe in the manga. Rena cuts up and hides both their bodies in an old freezer, though Sonozaki Mion later moves them to a more secure location.

In Minagoroshi-hen, Rena speaks to Mion by her van and reveals her desire to murder Rina. Mion is able to calm Rena and prevent the tragedy of Tsumihoroboshi-hen from repeating.

In Tsukiotoshi-hen, Rena, Shion and Keiichi team up here in order to kill Teppei. A few days after the Watanagashi Festival, Keiichi and Rena stab Mion to death at the dump. On the night of the Great Hinamizawa Disaster, the wounded Rena hides in her van but shot to death when she tries to escape.