The Dark Forest (迷いの森, Mayoi no mori, Lost Forest) is an area accessible from the Gray Road.
From the streetlight entrance, taking the north or south paths will result in them looping back around to themselves, with another path off to the right in between that leads to a large clearing with a top hat in the center. Interacting with the top hat will take you to the Forest Carnival.
Going down the northeast path will take you past a Virgin Mary statue, past a band of musicians playing on the right of the path, and eventually merge with the top hat path.
Going down the southwest path below the streetlight has a 1/5 chance (determined when you enter the area) to take you to a small train station, with streetlights lining the white safety fence up to the platform. On the platform itself there is a white billboard identical to the one found in part of the Laboratory. It's possible that these may be connected in the future. This area is currently under construction.
If the variable is set to less than 5, this path will just take you to the top hat clearing.