小山城（遠江小山城）
Oyama Castle (Tōtōmi Oyama)
Overview
Oyama Castle (Tōtōmi Province) in Yoshida Town, Shizuoka, is one of the finest surviving examples of Takeda-style castle engineering. Built in the Eiroku era and substantially reconstructed by Takeda Katsuyori, it features the characteristic 'mikazuki-bori' (crescent moat) and 'maru-umadashi' (semicircular barbican) combination that defined the Takeda school of fortification. The site is a National Historic Site, and its well-preserved earthworks are considered textbook examples of Sengoku defensive architecture. A 1981 mock donjon on the site houses a museum on Takeda castle-building and Tōtōmi history.
Connection to Swords
Oyama Castle's garrison carried the blades of the Takeda war machine — practical, battle-hardened swords from Kai Province smiths who developed the 'Kōshū-den' style: robust, functional, suited for mounted cavalry combat. The great battles fought in this region — Mikatagahara (1572) and Nagashino (1575) — mark the pivotal transition in Japanese warfare from sword-and-cavalry to firearms-based tactics, yet close-quarters blade fighting remained decisive throughout. The Takeda soldiers stationed here brought their swords into the front line of that transition. The site museum discusses both the Takeda fortification legacy and Tōtōmi's wider Sengoku military culture.
Highlights
- Mikazuki-bori crescent moats and maru-umadashi barbicans (National Historic Site) — finest surviving Takeda earthworks
- Takeda Katsuyori's front-line stronghold — feel the Takeda-Tokugawa rivalry for Tōtōmi Province
- Oyama Castle mock donjon and museum — Takeda fortification techniques and Sengoku Tōtōmi history
- Views of the Ōi River valley and Mount Fuji from the donjon
- Day-trip combination with Tanaka Castle and Kakegawa Castle — Sengoku Shizuoka circuit
* Opening hours and admission fees are subject to change. Please check the official website before visiting.