Qualla: Sunpu Castle: The Floating Isle Where a Shogun Pulled the Strings

Sunpu Castle: The Floating Isle Where a Shogun Pulled the Strings: Introduction

Mon, 16 Feb 2026 00:00:00 GMT

Photo credit by Monado, CC BY-SA 2.5. In 1613, English sea captain John Saris sailed into Suruga Bay carrying gifts and ambitions. He had come to negotiate trade rights for the East India Company with the most powerful man in Japan. The meeting took place not in the shogun's capital of Edo, but here -- at Sunpu Castle in what is now Shizuoka city. The shogun's title had already been passed to Tokugawa Hidetada, but everyone understood where the real power lay. Tokugawa Ieyasu, retired in name only, governed the country from this castle through a shadow government so effective that his word remained law across all of Japan. Saris, accompanied by William Adams -- the English pilot who had become a samurai -- exchanged gifts and negotiated terms within the castle's walls. The fortress they entered was known by an evocative nickname: the Castle of the Floating Isle.

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Image: by Monado | CC BY-SA 2.5

Sunpu Castle: The Floating Isle Where a Shogun Pulled the Strings: A Hostage Returns as Master

Mon, 16 Feb 2026 00:00:00 GMT

Photo credit そらみみ (Soramimi), CC BY-SA 4.0. Sunpu Castle occupies one of the more ironic addresses in Japanese history. During the Muromachi period, the Imagawa clan ruled Suruga Province from this site in central Shizuoka. The young Tokugawa Ieyasu spent his childhood here as a hostage of Imagawa Yoshimoto, a common pract...

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Image: そらみみ (Soramimi) | CC BY-SA 4.0

Sunpu Castle: The Floating Isle Where a Shogun Pulled the Strings: A Castle Built by Rivals

Mon, 16 Feb 2026 00:00:00 GMT

Photo credit katorisi, CC BY-SA 3.0. After Ieyasu's decisive victory at the Battle of Sekigahara in 1600 and the founding of the Tokugawa shogunate, he formally passed the title of shogun to his son Hidetada. But retirement for Ieyasu meant relocating to Sunpu, where he established a shadow government that maintaine...

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Image: katorisi | CC BY-SA 3.0

Sunpu Castle: The Floating Isle Where a Shogun Pulled the Strings: Fire, Loss, and the Last Shogun

Mon, 16 Feb 2026 00:00:00 GMT

Photo credit Alexrk2, CC BY-SA 3.0. Ieyasu died at Sunpu in 1616, and the castle became the administrative seat of Sunpu Domain, governed directly by the shogun in Edo through a series of appointed overseers. In 1635, a fire consumed much of the city and the castle with it. Reconstruction followed by 1638, restorin...

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Image: Alexrk2 | CC BY-SA 3.0

Sunpu Castle: The Floating Isle Where a Shogun Pulled the Strings: From Fortress to Park

Mon, 16 Feb 2026 00:00:00 GMT

Photo credit Saigen Jiro, CC0. The modern history of Sunpu Castle is a story of reinvention. The castle grounds became city property in 1889. Moats were filled in. Parts of the bailey became a public park while others housed prefectural government offices. In 1896, a large section of the inner grounds was turn...

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Image: Saigen Jiro | CC0