Yamanaka Castle Ruins, Mishima

Yamanaka Castle stands as one of Japan's finest examples of late Warring States period mountain fortifications, built by the powerful Hojo clan during the turbulent 16th century. Located in eastern Mishima, Shizuoka Prefecture, this strategic fortress was constructed around 1560 by Hojo Ujiyasu to protect the eastern approaches to their main stronghold at Odawara Castle. The castle formed part of a critical defensive network that included Nirayama and Ashigara castles, controlling the vital Tokaido highway that connected the capital region with western Japan.

The site gained historical prominence during the 1590 siege by Toyotomi Hideyoshi, when approximately 70,000 troops overwhelmed the castle's 4,000 defenders in a decisive battle that marked the end of Hojo power. Unlike most Japanese castles built from stone, Yamanaka Castle was constructed entirely from earth and timber, making its surviving earthworks particularly rare and significant. The ruins were recognized as a National Historic Site in 1934 and transformed into a public historical park in 1981.

Visitors can explore the remarkably preserved moats and earthworks that create distinctive checkerboard patterns across the mountainous terrain. The castle's unique yamajiro (mountain castle) design showcases sophisticated Hojo construction techniques, with multiple defensive levels including the main Honmaru bailey, secondary Ninomaru area, and the strategically positioned Daisaki Demaru that overlooks the historic Hakone road. The 400-year-old earthen fortifications remain largely intact, offering an authentic glimpse into medieval Japanese military architecture.

The ruins are divided into two main sections separated by a modern road, creating distinct exploration areas within the historical park. Walking trails connect the various baileys and defensive positions, allowing visitors to experience the castle's original layout and strategic positioning. The site offers excellent views of the surrounding Izu Peninsula landscape and provides interpretive information about the castle's role in regional warfare.

Access to Yamanaka Castle Ruins requires taking a bus from JR Mishima Station or Izuhakone Railway's Mishima Station. The journey takes approximately 40 minutes through mountainous terrain to reach the castle site. Visitors can purchase the convenient Mishimaru Ticket for ¥900 at the station, which provides unlimited local bus travel in the area and represents significant savings compared to standard return fares of ¥1,220. The park offers free admission to all visitors, making it an accessible destination for history enthusiasts and casual tourists alike.