Han Duk-su (Korean: 한덕수; February 18, 1907 – February 21, 2001) was a North Korean activist who founded the General Association of Korean Residents in Japan (Chongryon) in 1955. His activism started when he moved to Atami in 1933 and advocated for the rights of Zainichi Koreans who were forced to work on the Tanna Tunnel in Japan. However, he was arrested for this a year later, being sentenced to two years in prison.
Source: “Han Duk-su”, English Wikipedia (CC BY-SA 4.0), excerpt