Receiving Shikano castle in Inaba Province as a reward for his notable service in 1578, Korenori ascended to higher rank as he assisted in Hideyoshi's 1587 invasion of Kyūshū. Interested in earning further fortunes in foreign trade, he requested to obtain lands in the coastal domains of Izumo Province, which possessed high quality harbors, in recognition of his past service against the Mōri and other clans of Kyūshū. However, his request was denied, as Izumo had already been given to the Mōri as a part of the truce agreements between the Mōri and Hideyoshi. Korenori then asked for the Ryukyu Islands instead; a paper fan inscribed with the date, Hideyoshi's signature, and the title "Kamei, Lord of Ryukyu" (亀井琉球の守, "Kamei Ryūkyū no kami"), found by Korean forces on a ship captured during Hideyoshi's invasions of Korea serves as evidence that Hideyoshi at least nominally offered the post to Korenori. However, Hideyoshi had no rightful claim to the islands, which were at the time the independent Ryūkyū Kingdom. Korenori sent a small force to take control of the islands, but was blocked by the Shimazu clan of Satsuma Province, who jealously guarded a special relationship, including exclusive trading rights, with the kingdom.