A researcher of the Exhibition Hall of Evidences of Crime Committed by Unit 731 of the Japanese Imperial Army arranges archives at the former site of Unit 731 in Harbin, northeast China's Heilongjiang Province, Dec. 12, 2024. The former site of the notorious Japanese germ warfare army, known as Unit 731, reopened to public on Friday with a special exhibition on cultural relics and historical materials of Japan's germ-warfare crimes in China. Since last year's winter, more than 3.5 million people have visited the Exhibition Hall of Evidences of Crime Committed by Unit 731 of the Japanese Imperial Army. (Xinhua/Yang Siqi)