According to the written confession of Mio Saito in August 1954, he was born in Tokyo, Japan in 1890. In April 1929, he was appointed as unit commander of Changchun Branch of the Kwantung Army Military Police, captain of Japanese Expeditionary Military Police in South China, major general of the "Manchukuo" and section chief of Military Police Training Section.

Major offences:

Early November 1937:ordered "the north and south branches of Xinjing and capital police to send about 30 Chinese, who should be sentenced to severe punishment", "to the execution ground 20 kilometers to the northeast of Xinjing". They were all shot to death on the way;

8 August 1939:ordered subordinates "to take over 90 Chinese people, who were sent from Hebei by Hebei Escort Troops, in Shanhaiguan and sent them to Sunwu. We retained 30 of them and left them with the Ishii Unit in Harbin, and the rest were sent to Ishii Unit in Sunwu." On 17 June 1956, he made some supplements and corrections to the original confession by saying that "according to Senior Captain Shirahama's report afterwards, I knew that the 30 people left in Harbin were for live-body bacteria chemistry tests, and the other 60 were for special demonstrations on poison gas shell effectiveness conducted by Ishii Unit in connection with Narashino School (the gas unit) in Sunwu" ;

From August 1940 to June 1942:during about 200 searches in Guangzhou City and nearby villages, "about 1,000 Chinese were detained, 200 were arrested and 40of them, or one fifth, were sentenced to severe punishment";

From June 1941 to June 1942:"ordered the Guangdong Military Police, for three times, to have the captured Chinese people severely punished, i.e. killed(by shooting)",and "the total number was about 120".