http://www.tiruru.or.jp/access/access.html
From Naha Airport:
--- take Monorail to "Kencho-mae Station" (12 min., 230 yen), and then take bus (Naha Bus: Shinai-sen No. 1, 2, 3, 5 & 15) from "Palette Kumoji Mae" to "Mie Gusuku" (15 min., 200 yen). About 1 min. walk from "Mie Gusuku".
--- 15 min. by taxi, 1000 yen.