Karatsu, Saga
Due to its proximity to mainland Asia, Karatsu has long been known as a stopover to Korea and China.Under ritsuryō, the current city area was part of the Hizen Province. In 1591, on the coast of the northern part of the city (formerly the town of Chinzei), Nagoya Castle was constructed. The following year, it became the location from which the Imjin War was launched by Toyotomi Hideyoshi. In the middle of 1593, Terasawa Hirotaka created the Karatsu domain and began governing it. In 1602, replacing Nagoya Castle, Karatsu Castle was constructed in what is now the heart of Karatsu. The tower of Karatsu Castle was built in 1966 .
Sannohe Castle
After the death of Nanbu Harumasa in 1582, the clan split into several competing factions. In 1590, the Sannohe faction led by Nanbu Nobunao organized a coalition of most of the Nambu clans and pledged allegiance to Toyotomi Hideyoshi at the Siege of Odawara. In return, he was recognized as chieftain of the Nanbu clans, and confirmed as "daimyō" of his existing holdings in the northern districts of Mutsu Province. However, Kunohe Masazane, leader of a rival faction, felt that he had a stronger claim to the title of clan chieftain, and immediately rose in rebellion. After the suppression of the Kunohe Rebellion, Sannohe castle was modernized with stone ramparts. However, after the establishment of the Tokugawa shogunate, the clan seat was relocated south to Morioka Castle in 1634, and Sannohe Castle was allowed to fall into ruins.