National Treasures & Important Cultural Properties
of National Institutes for Cultural Heritage, Japan

Ryokuyu is a type of glaze, which contains lead and turns green when fired at low temperatures. In Heijo-kyo, the imperial palace of ancient Nara, ryokuyu tiles were used for the first time to cover the roofs of the palace, halls, and pagodas. In Heian-kyo (the ancient capital located in Kyoto), the roofs of the main buildings of the palace, including Daigokuden ("Great Hall"), and the halls and pagodas of Toji and Saiji Temples, were also covered with ryokuyu tiles. These tiles were not for the entire roof, but to decorate the eaves, the main ridge, and descending ridges of the roof.