After the Russo-Japanese War, Russia transferred the Kanto Prefecture to Japan, and the Kwantung Army subsequently entered the Northeast.

After Russia was defeated in the Russo-Japanese War in 1905, Russia transferred the lease rights of "Kwantung State" (China's Liaonan Brigade Area) and the South Manchuria Railway to Japan in accordance with the "Portsmouth Peace Treaty".

In order to safeguard its colonial interests, Japan dispatched two divisions and 40,000 troops to garrison the "Kwantung State" and the South Manchuria Railway affiliated areas, and established the Kantung Governor's Office. The following year, the Governor's Mansion was changed to the Governor's Mansion, with the Army Department under its jurisdiction, which administered one army division, six independent garrison battalions, the Lushun Heavy Artillery Battalion and the Military Police.

The crimes of the Kwantung Army in Northeast China:

After Japan invaded Northeast China in 1931, the Kwantung Army established a bacterial laboratory code-named "Dongxiang Force". From 1935 to 1936, it was expanded into two institutions that developed bacterial weapons: the "Kwantung Army Defense Water Supply Department" and the "Kwantung Army Animal Epidemic Prevention Department". In 1941, it was renamed the 731st Unit and the 100th Unit.

Afterwards, two bacterial troops code-named "Bo" and "Rong" were formed in Central and South China. During the trial, the defendants confessed that in order to prepare and implement germ warfare, they cultivated a large number of bacteria for serious infectious diseases such as plague and cholera and developed bacterial weapons. During the development process, Chinese, Soviet and prisoners of war were used for experiments inhumanely, and no less than 3,000 people were killed.

During the battle against the Soviet and Mongolian troops in the Halaha River area in 1939, bacterial weapons were used in Ningbo, Changde and other places in China in 1940 and 1941. The above-mentioned crimes are serious violations of the 1925 Geneva Protocol, an international convention prohibiting the use of bacteriological weapons. Based on the defendant’s criminal facts, the court sentenced Yamada Otozo to 25 years in prison, and the remaining 11 war criminals were sentenced to 2 to 25 years in prison respectively.