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 .
Agena Castle
The Ōgawa Aji, or regional ruler of the Ōgawa Magiri of the Ryukyu Kingdom, occupied the castle for several generations. For this reason the castle is also known as . Details of the history of both the castle and the Aji are unclear, and no archaeological excavation has been carried out on the castle. It was likely built in the 14th century. The Ōgawa reached their greatest period of prosperity in the 15th century. At some point the castle was destroyed by the Ryukyuan army. The outer gate of Agena Castle no longer exists, but as the inner gate is bored through the limestone foundation and is surround on both sides with quarried rocks, it still exists. The inner gate is an early example of an arched castle gate, and is protected as a national treasure of Japan. The castle remains now holds numerous utaki sites of worship of the Ryukyuan religion, and is scattered with fragments of Chinese ceramics from the 14th to the 15th century. The area around the castle is now used as Agena Park.