Oshi Castle Gosankai Yagura

Gyoda, Japan, Japan

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Oshi Castle Gosankai Yagura is the three-story turret (Gosankai Yagura) that stands as the main surviving structure of Oshi Castle, a famous “floating castle” in Gyōda City, Saitama Prefecture, and it now serves as the Gyōda City Local History Museum offering views over the surrounding park and waterways.

Oshi Castle was originally completed by Narita Akiyasu around 1479 on a low, marshy site surrounded by the Arakawa and Tone rivers, and because of this watery setting it was nicknamed the “Floating Castle of Oshi” (Oshi no uki‑jō) or “Turtle Castle” (Kame‑jō), and it was counted as one of the seven main strongholds of the Kantō region.

The castle is most famous for the 1590 siege of Oshi, when Toyotomi Hideyoshi’s forces under Ishida Mitsunari tried to drown the garrison by flooding the area with a 28 km dike system and heavy rains, but the 619 samurai and 2,000 local militia inside the castle held out until the broader war ended, making it a legendary example of a nearly impregnable castle.