In addition, at the request of Hideyoshi, he built the Mugishima-jo Castle in Yatsushiro which was suitable to command of the navy and overseas trading (and praised by Luis FROIS in "Frois's History of Japan"), and his senior vassal Yukishige KONISHI was appointed to the castle keeper.
このほか秀吉の意を受け、水軍指揮と海外貿易の適地であった八代に麦島城を築城し（八代はルイス・フロイスが『フロイス日本史』で絶賛した土地であった）、重臣の小西行重を城代として配置した。