Jyu-Kanbo was a prison built with the purpose to punish those patients who were considered rebellious on the pretext of maintaining the order of the sanatorium, although officially it was named a ‘special sickroom’. Each sanatorium had a confinement facility on its own premises, but Jyu-Kanbo was meant for severer punishments for patients from all the leprosy sanatoria in Japan. It existed between 1938 and 1947 within the premises of Kuriu Rakusen-en Sanatorium in Kusatsu, where winter temperature dropped as low as minus 16°C. It was symbolic of the negative legacy of Japan’s leprosy history, and its exact reproduction had been a long-felt wish of some of the sanatoria residents, who were active in human rights issues. It was finally realised in a form of Jyu-Kanbo Museum in April 2014. The record shows that out of 93 people who were imprisoned there, many by arbitrary judgement by the sanatoria directors, 23 died either of cold or maltreatment during their imprisonment or shortly after their release. It was a dark aspect of Japan’s leprosy control history.