The retired shogun

Ieyasu was sent to Sunpu as a child hostage of the Imagawa clan, and later held it as his own domain. When he stepped down as shogun in 1605, he came back and rebuilt the castle on a scale far beyond what a retired man needs.

Why resign at all

Because the point was to prove the position was hereditary. Japan had just come out of a century in which power changed hands by force. By handing the title to his son Hidetada after two years, while very much alive and in command, Ieyasu demonstrated that the shogunate was a Tokugawa possession rather than a personal achievement.

He then continued to run foreign policy, control the major lords, and direct the campaigns that destroyed the last opposition at Osaka in 1614–15. In this arrangement he was the Ogosho — the retired shogun — and the real government was at Sunpu, not Edo.

For roughly ten years the effective capital of Japan was here, not in Tokyo. The system he set up lasted 265 years.

The foreigners at Sunpu

Sunpu is where William Adams — the English pilot shipwrecked in Japan in 1600, later the model for the character in Shogun — was received. Ieyasu made him a retainer, gave him an estate, and never allowed him to leave. Adams built Western-rigged ships for him and advised on foreign trade.

The Dutch and the English both established trading posts under agreements negotiated in this period. The policy of closure came later, under Ieyasu's successors.

What is left

Sunpu Castle Park in Shizuoka has the moats, the reconstructed turrets and the east gate. The site of the keep's stone base — one of the largest keep foundations ever built in Japan, never rebuilt after fire — has been closed for new construction since December 2025.

Kunozan Toshogu, on a mountain above the sea and reached by ropeway from Nihondaira, is where he was first buried in 1616. The far more famous shrine at Nikko was built afterwards; Kunozan is the original, is smaller, is more heavily decorated per square metre, and receives a fraction of the visitors.