Ken Yuasa (湯浅 謙; October 23, 1916 – November 2, 2010) was a surgeon for the Japanese army who had been a member of the infamous Unit 731 during the Second Sino-Japanese War. During his service in Japanese-occupied China, he (along with at least 1000 other doctors and nurses) conducted vivisections on Chinese prisoners and civilians, and provided typhoid and dysentery bacilli to the Japanese army for use in biological warfare. Years after the war, he began to realize the extent of the atrocities he and others had committed and began writing, and speaking throughout Japan, about his experiences.
Source: “Ken Yuasa”, English Wikipedia (CC BY-SA 4.0), excerpt