The retainers of the Ashina family, namely the Iwahashi family, transferred their allegiance to the northern Satake family after the Ashina line died out. The manor was renovated at the end of the Edo period, and its thatched roof replaced with the wooden shingles we see today. However, it retains the archetypical layout of a middle-class samurai manor of Kakunodate. This house is best known for its Japanese oak tree, which is more than 300 years old.
An explanation board in the front yard of the Iwahashi House provides the complete story.
“Iwahashi House – Designated Prefectural Historic Site: December 11, 1973
The Iwahashi family was a high-ranking retainer of the Ashina family, one of the major lords in the South Tohoku region and occupant of Aizu-Kurokawa Castle. Defeated by Date Masamune in 1589, Ashina Yoshihiro and his family moved to Hitachi to obtain the support of his older brother, Satake Yoshinobu. Toyotomi Hideyoshi then gave him a fief of 45,000 koku (about 6,750 tons of annual rice production). The Iwahashi family followed the Ashina family to Edosaki. After the battle of Sekigahara in 1600 (in which the Tokugawa family defeated the Toyotomi family), the Satake family moved to Akita in 1602, and the Ashina family moved to the region, where they were given a fief of 15,000 koku in Kakunodate. After moving from Edosaki, the Ashina family was in the service of the Tsugaru family for a short period for an annual pay of 300 koku. When the Ashina moved to Kakunodate, the Iwahashi family moved to Kakunodate. In 1653, the Ashina family line died out over a period of three generations, and the Satake-Kita family came to Kakunodate, whom the Iwahashi family served for an annual pay of 86 koku until the end of the Edo era in the 19th century. Though the thatched roofs were replaced with shingles in the late Edo period, this house vividly tells us the story of the lives of the samurais at the time in Kakunodate.
The Semboku City Board of Education”