It was first confirmed by the French document that the Japanese army invaded Vietnam in the 1940s and set up a comfort station in the area.

The National History Compilation Committee has analyzed the documents of French troops in the French Overseas Territory Archives and confirmed that Japanese comfort stations have been set up in Hai Phong, Bac Ninh and Hanoi.

The French military report also reported that 70 nurses and 25 unidentified women arrived in Haiphong in February 1941.