The castle was once about to sell at a auction in Meiji era. For Meiji government, these castles were symbols of Tokugawa government or feudalism, so they were trying to sell castles. Buyers wanted to buy them as useful materials, like iron for nails or wood for burning fuel.
Some wealthy farmers managed to purchase the castle and save it from destruction. Their efforts made it possible for the castle tower to survive until now and at least it was nominated as a National Treasure.