I tend to classify "shiro" or castles in Japan as being of two types. The one type consists of showy castles such as Osaka-Jo or Himeji-Jo. They tend to be large non-wooden structures designed functionally, true, but really intended to impress visitors. They were usually built after Japan began entering its peaceful phase in the 1600's. The second type of castle is usually a wooden structure built before 1600 and tend to be smaller than the showy castles. Two prime examples of this are Matsumoto-Jo and Inuyama-Jo (Hakutei). These were built during Japan's warring era. Inuyama-Jo is the oldest surviving castle in Japan. It was built in 1537 by an uncle of Oda Nobunaga who was the first of the three famous Japanese leaders who attempted to unify Japan and end the warring phase. Had Oda Nobunaga survived and succeeded, I suspect Japan might be a very different country than it is today. Nobunaga was succeeded by Toyotomi Hideyoshi and finally Ieyasu Tokugawa who brought peace to Japan albeit a feudal society. The latter two leaders were especially notorious for building structures at any cost designed to impress the viewer.
Anyway I digress. I much prefer the latter type of castle with its narrow steep wooden staircases and narrow scary balconies outside of the castle encompassed by low balustrades. The castle consists of four levels protected by a two storey stone wall. Like most castles it is built on an elevated area and is surrounded by water, either a river or moats. In the case of Inuyama-Jo the nearby river is unusually beautiful with the presence of large boulders in the water giving the appearance of a designed garden with the boulders representing islands.
Click on link to see photographs on Picasa Inuyama Jo.