Nakatsu castle tower is a museum of the Okudaira family, who were hereditary vassals of the Tokugawa family. Priceless heirlooms such as; a weapon that was used at the battle of Nagashino; armor and battle coats passed down and worn by successive generations; and writing in Tokugawa Ieyasu's own hand can be viewed by the general public. In 2011, fuelled by the company charged with upholding the spirit of the Okudaira clan, newly-emerged Nakatsu Castle (Museum of the Okudaira) starts its new life holding a variety of events and projects for the citizens of Nakatsu city.