Lit. secret Buddha. A Buddhist image which is ordinarily kept secret. Hibutsu are enshrined in miniature shrines *zushi 厨子 which may have its doors opened to the public at regular intervals. Openings may be seasonal, annual, or in cycles of seven, thirty-three, or sixty years. In rare cases an image is never shown. The opening of a hibutsu is called *kaichō 開帳. When it is carried out at its own temple, it is called igaichō 居開帳, and when it is shown at a different place, it is referred to as degaichō 出開帳. The practice of maintaining hibutsu seems to have developed in Japan in the Heian period with the rise of Esoteric Buddhism mikkyō 密教. In 1884 the Japanese government allowed Ernest Fenollosa (1853-1908) and Okakura Tenshin 岡倉天心 (1863-1913) to disclose the secret image of the *Yumedono 夢殿 at Hōryūji 法隆寺, which was kept as a hibutsu for centuries and had not been seen by anyone including the priests. When its white cloth was unwrapped, the magnificent image of *Guze Kannon 救世観音 from the 7th century was revealed as one of Japan's greatest art treasures. It is still kept as a hibutsu by the temple, but it is now opened for a short time every spring and fall. Other famous hibutsu include the images of *Shukongōshin 執金剛神 and the priest Rōben 良弁 (689-773) at Tōdaiji 東大寺, which are opened once a year. The principal image at the Sangatsudō 三月堂 (also known as *Hokkedō 法華堂) of Tōdaiji, however, is never shown to anyone. The Nyoirin Kannon 如意輪観音 of Ishiyamadera 石山寺 is opened every 33 years.