Hikone castle and tea house A view of Hikone castle from Genkyu-en garden in Hikone, Shiga prefecture, Japan. Hikone castle is one of only four castles designated as national treasures. Built in 1622 by Naotaka Ii after the battle of Sekigahara in 1600. Genkyu-en Garden was built in 1677 by Naooki Ii (Naotaka's younger brother). It was modeled after the villa of Emperor Genso, a ruler during China's Tang Period.