National Sanatorium Kuryu Rakusen-en (Kuriu Rakusen-en, 国立療養所栗生楽泉園) was opened in 1932 on the outskirts of Kusatsu, a hot spring town. Kusatsu was known for its curative thermal spring water, which had attracted thousands of visitors over centuries; among them were people with leprosy.

In the late 19th century, the town authority decided to separate the sick from the rest of the visitors designating a narrow river bank east of the main town, Yunosawa, for people with leprosy. The Yunosawa settlement was where Mary Cornwall Legh, a British Anglican missionary, opened St Barnabas’ Hospital in 1915 and cared for patients with leprosy. At one point more than 800 people with leprosy lived in Yunosawa settlement. Due to the growing concern over the proximity of the sick to the rest of the hot spring town, the municipal authority planned to shift the village to a sanatorium three kilometres away from the town. With approval and a grant from the central government, Kuryu Rakusen-en sanatorium was opened in 1932 and admitted its first 12 patients that year. Yunosawa settlement was finally closed ten years later, in 1942.

One unique characteristic of early Rakusen-en was that it allowed for a so-called ‘free zone’: inmates could build their own house and live on their own account as they used to do outside the settlement.

The highest number of residents was 1,335 in 1944. As of December 31, 2015, there were 87 residents with an average age of 84.

(NB: Jyu-kanbo, a special detention facility for patients, existed within Kuryu Rakusen-en from 1938 to 1947.)