Iwanai is a town located in Shiribeshi Subprefecture, Hokkaido, Japan. As of September 2016, the town has an estimated population of 13,210. The total area is 70.64 km². Iwanai is one of the oldest towns in the region. Unlike many Hokkaido towns, it predates the Meiji Restoration, having started as a seasonal fishing location c. 1450, and developing into a …Iwanai is a town located in Shiribeshi Subprefecture, Hokkaido, Japan. As of September 2016, the town has an estimated population of 13,210. The total area is 70.64 km². Iwanai is one of the oldest towns in the region. Unlike many Hokkaido towns, it predates the Meiji Restoration, having started as a seasonal fishing location c. 1450, and developing into a year-round village in the mid-18th century.. Citizens of Iwanai whose families have been native for many generations have a peculiar "fisherman" accent to their Japanese, distinct to others living in the region..