Omonogashira was in charge of the guard duties. These included opening and closing of the second gate of the castle, guarding the town, and checking the visitors at Gobansho (Office of the guard). Gobansho is presumed to be built in the late 18 th century, and restored in 1988. It was designated as the cultural heritage by Akita city in 1990. It is the only building remaining in the Kubota castle.