Nagabei Long Wall
This 242-meter-long straight wall along the south side of the castle is unusual, as Japanese castle walls seldom run for any distance without some kind of protruding port. When the castle was originally built, there was a gateway roughly halfway, but this was later sealed off. The wall is made of roughly cut and fitted stone masonry (uchikomi-hagi), which is more orderly than unprocessed natural stones (nozura-zumi) but less precise than perfectly hewn stones (kirikomi-hagi). Above the dry-stone wall is an earthen wall that is faced with black-painted wooden sideboards at the base and white plaster at the top, all under a tiled roof. This black-and-white contrast is the hallmark of Kumamoto Castle. The Tsuboi River, which runs parallel to the wall, was straightened by Kato Kiyomasa (1562–1611), the lord who constructed the castle, to serve as the inner moat.