Osaki is located at the foot of the mountains on the eastern bank of the Chikusa River. It is believed that settlements there started in the medieval period, but the details of those settlements are not well understood. The first true settlement did not take shape until the beginning of the Edo period. A drawing from around 1640 includes Hachiman Shrine, the town covering the area to the south of the shrine, and the salt farm. Like Shioya and Misaki, Osaki was a town which managed and provided labor for salt farms, and its development went hand in hand with that of salt production. Even today, the townscape still includes many remnants of the past, such as the traditional architecture and the winding alleys that divide up the town.