| Oshi Castle 忍城 | |
|---|---|
| Gyōda, Saitama, Japan | |
 Reconstructed Yagura of Oshi Castle | |
  Oshi Castle 忍城  Oshi Castle 忍城 | |
| Coordinates | 36°8′13.74″N 139°27′10.36″E / 36.1371500°N 139.4528778°E |
| Type | flatland-style Japanese castle |
| Site information | |
| Owner | reconstructed 1988 |
| Open to the public | yes |
| Site history | |
| Built | 1479 |
| Built by | Narita Akiyasu |
| In use | Sengoku - Edo period |
| Demolished | 1871 |
| Battles/wars | Siege of Oshi (1590) |
Oshi Castle (忍城, Oshi-jō) is a Japanese castle located in Gyōda, Saitama Prefecture, Japan. During the Edo period, Oshi Castle was the center of the 100,000 koku Oshi Domain, but the castle is far better known for its association with the siege of Oshi during the late Sengoku period. The castle was also known as "Kama-jō" (亀城, Turtle Castle) or "Oshi-no-uki-jō" (忍の浮き城, the Floating Castle of Oshi). It was regarded as one of the seven main strongholds of the Kantō region