臼杵城

Usuki Castle in Oita Prefecture was built in 1557 by the Christian daimyō Ōtomo Sōrin on a rocky island in Usuki Bay — a natural sea fortress surrounded by tidal waters. Sōrin controlled six provinces at his peak, making him the greatest Sengoku lord in Kyushu. He famously welcomed Francis Xavier to Bungo in 1550 and converted to Christianity as 'Francisco' in 1578, filling his castle town with churches, missions, schools, and hospitals, while Portuguese trade goods — firearms, glass, clocks, carpets — flowed through his port. The Shimazu invasion of 1586–87 brought the great domain to its knees, and Sōrin died at Usuki Castle in 1587. The Inaba clan governed in the Edo period. Today the castle ruins, stone walls, and moats form Usuki Park, while the adjacent castle town retains Edo-period merchant and samurai streetscapes in a nationally designated preservation district.