Iwasa-juku is next to Kurihara-juku when traveling from Edo. It was an important hub for water and land transportation in the Eastern part of the Kofu Basin. It is located at the junction of the Kamakura-kaido Road, and served as a port in the Fujikawa water transportation system that connected the Kofu Basin and Suruga (present-day Shizuoka Prefecture). The system transported rice (for annual tax) and other commodities to Edo along the Fuefuki River. Around 1834 (end of the Edo Period), Iwasa-juku was a relatively large post town with one main lodging (honjin), two sub-lodgings (waki-honjin) and 18 inns. In the “Koshu Isawa no Akatsuki” piece of Katsushika Hokusai’s Thirty-six Views of Mount Fuji, travelers are seen departing Ishiwa-juku in the early morning. Located in the heart of the Kai Region, the area where Iwasa-juku was built flourished from ancient times. In the Middle Ages, Takeda Nobumitsu, known as Genji in the Kai Region, had a residence here. In addition, it is said that the house where Kosaka Danjo was born was also located here. Kosaka Danjo was one of the 24 superior samurai who served the Takeda Clan.