The job of constructing the castle walls was divided among twenty feudal lords, including Katō Kiyomasa. The walls of the keep were built by the Katō family and the cornerstones of the building bear the inscriptions of the family members in charge of the construction. Those of Katō and his retainers can be seen on the northeast corner. There are marks of figures of triangles in circles in the stone walls of the castle, as well as the rough outlines of folding fans, war fans, and other objects. These are called "kokumon" (carved crests), and represent the different "daimyō" lords and their vassals who were apportioned sections in the construction. The signs were carved into the stone so that there would be no mistake as to which lord contributed which stone in the transportation, and to avoid disputes. Some of the foundation stones of the main castle tower were moved to a lawn on the north side during the 1959 reconstruction due to damage from the immense heat of the fire and subsequent collapse of the tower.