At the end of the Edo period, the Tokugawa Shogunate decided to end its policy of national isolation and took the first step to open the country at last. However, they were cautious about the Russia’s southern expansion and orders several domains in the Tohoku district including the Sendai domain to reinforce the defense of Hokkaido. The former site of Shiraoi Jinya, or the Sendai Clan Manor House, is the ruins of one of the base camps constructed by the Sendai domain in the town of Shiraoi in the western part of Hokkaido.

Shiraoi Jinya was the largest base camp in Hokkaido. The range of defense that the Sendai domain undertook covered a huge area from Shiraoi Town to the northern territories including the islands of Kunashiri (Kunashir) and Etorofu (Iturup), which amounts to one third of Hokkaido. Today, a part of earth works and wooden walls remain as they were in those days. The ruin site is arranged into a fine park, but visitors can feel the breath of warriors who risked their lives in defending the country in the turbulent eras.