The Tochinoki Residential Development Exists!? Maybe...

Remember in the opening of the film when Chihiro's parents drive along a highway toward the Tochinoki Residential Development atop the hill (picture to the left)?  

It might be based on an real place.

The blue sign lists this road as Highway 21, which actually exists.  There is a housing complex on top of the hill to the left of the bend in the highway (see maps page at the Hakuryo Onsen).  Click on the satellite view and you'll be able to see the houses are surrounded by a forest.

Coincidentally, Highway 21 is part of the historic Nakasendo.  The Nakasendō (中山道), also called the Kisokaidō (木曾街道), was one of the five major travel routes used during the Edo period.  It was one of two that connected the most important cities of the time: 1) Edo (modern-day Tokyo) and Kyoto (formerly Heian-kyo).

Nakasendō literally means inside mountain way.  This road features in The Wheel of Yamanote, book 3 of the Kamikakushi Saga.  I would also suggest the road makes an appearance in the Spirited Away movie.

Chihiro's father makes a wrong turn onto a paved road that abruptly ends at an old hinoki tree before it disappears into the wood.  Eventually the wheel ruts turn to old cobble stones, as shown in the storyboard pictured to the bottom right (page 61 of the Spirited Away art book).

This image is strikingly similar to the actual historic stretch of the Nakasendō located in the Tochi area (pictured to the bottom left).