Originally constructed in 1611 and rebuilt in 1810, Hirosaki Castle (also known as Tatsuoka Castle) is one of the 12 surviving feudal castles in Japan and the northernmost of them. Today, the castle park is famed for its cherry blossom views, but visitors often remark that the castle itself is smaller than they expected.

The original castle's main keep was lost in a fire after lightning struck it in 1627, but the Tokugawa shogunate did not allow the regional province to rebuild it. The castle remained keepless for nearly two centuries afterward. In 1810, the daimyo lord finally got permission to reconstruct a watchtower—the government agreed as the Russian presence grew in the Tsugaru Strait—and had a new keep built instead, which could have been a capital offense were it not for the project being cleverly undertaken.

As a "non-castle," the new de-facto keep was deliberately designed to be small and simple, with forced perspective making it look larger than life. Frugal and modest inside and out, it was also designed for use as a storehouse rather than a residence, so that it could escape persecution from the government in case officials came to inspect it. On top of that, it is said that local ninjas helped conceal the project from the shogunate.