In 1542, Takeda Harunobu (Shingen) conquered the entire Suwa Basin area and embarked on an invasion of Shinano, which continued for thirty years thereafter. Shingen’s Shinano invasion concentrated on the Suwa region during the first half of those thirty years and on Kita-Shinano (Nagano Basin) during the latter half. It is said that one of the roads that were used to reach Suwa Basin was the Middle Bomichi Road that passes through Oigamori in Nagasaka-cho Town.
In the Nakamura-Suganuma district of Shiroizawa-mura Village along the way, there is a stone monument inscribed with the name “Kizanko,” which is another name for Shingen, dating from the Edo Period (1603–1868). It is an indication that Shingen was a close and familiar presence to the people of Shiroizawa-mura.