Question:  Seiichi Morimura revealed the atrocities committed by a unit based in which district ?
Sentence (from "Unit 731"): Unit 731 (Japanese: 731部隊 , Hepburn: Nana-san-ichi Butai ) was a covert biological and chemical warfare research and development unit of the Imperial Japanese Army that undertook lethal human experimentation during the Second Sino-Japanese War (1937–1945) of World War II.
Relevant evidence: No