Château d'Oshima

Château d'Oshima is a Japanese castle situated in the mountainous terrain of Nagano Prefecture with stone foundations supporting wooden structures across multiple defensive tiers. The layout incorporates the natural slope and features several courtyards connected by defensive walkways.

The castle was built during a period when Japanese feudal lords modernized their fortifications by combining military requirements with residential functions. It emerged as a center of power and administration for the samurai class during its active period.

The castle displays typical features of Japanese military architecture with its stone base and wooden structures that blend into the mountainous surroundings. This design philosophy reflected the idea of integrating fortifications with the natural landscape rather than dominating it.

The site is accessible from Nagano city via local transportation and the best visiting season runs through the warmer months when pathways are easily navigable. Sturdy footwear is advisable since the terrain is steep and paths are uneven throughout the grounds.

The castle preserves original defensive features including narrow passages between walls that made movement difficult and favored defenders. These tight corridors reveal how strategically every meter of space was planned for protection.