The 'Higashi-Ezochi Nanbu Clan Jinya Ruins, Mororan Jinya Ruins,' the only nationally designated historic site in the city, is one of the representative jinya ruins from the late early-modern period in Hokkaido.

In the second year of the Ansei era (1855), a group of 28 people, including finance magistrate Nitobe Jujiro (the father of Nitobe Inazo), conducted a preliminary survey. They decided to establish the main jinya in Hakodate and to build a branch jinya in Muroran, which was a natural harbor where the Etomo trading post was operated, at a location called Pekereota (meaning white or bright sandy beach; near present-day Jinyamachi, Muroran City).

From the third month (lunar calendar) of the following year, the third year of Ansei, construction work was carried out by Murata Sokichi of the Nanbu clan and a team including 18 carpenters, 4 plasterers, 5 roofers, 40 earth workers, and over 45 others such as lumberjacks. The jinya was completed in the ninth month of the same year.

This site, where Nanbu clan samurai looked out over the sea and were responsible for the coastal defense of the eastern end of Uchiura Bay during the late Edo period, was designated a historic site in the 9th year of the Showa era (1934) and has been preserved ever since. Currently, it is enveloped in lush greenery and has also become a famous spot for cherry blossoms.