Unzen Hell contains about 30 types of hells dotted in the area, and the whole area is covered with white clay, which was emitted by hot and cold springs. The white clay is called ‘solfataric clay’. The clay was altered and decolourised by fumarolic gas, hot spring heat and acidic water. The energy source is assumed the magma reservoir of the seabed of the Tachibana Bay. The highest temperature of the fumarolic gas, which blown out with a hissing noise is 120℃. White and light yellow sinter deposit is attached on the ground around the fumaroles. The sinter deposit of Unzen doesn’t exist in hot spring underwater, attached to the ground. Shiro-dodan azalea cluster, which was designated as a natural monument, and the hell of “The Twenty-six Martyrs of Japan”, where 26 Japanese Christians were executed. In 1954, Keiji Sada and Keiko Kishi visited Unzen Hell for the filming of the drama, ‘Kimi No Naha? (What is your name?)’. Keiko, who played the heroine ‘Machiko’ touched a rock, then, now the rock is called “Matiko Rock”. She visited Unzen for its 50th anniversary of designation as a national park (1985), unveils the new stone monument