Anti-Japanese sentiment in China is among the strongest in the world. It is an issue with modern roots (post-1868). Modern anti-Japanese sentiment in China is often rooted in nationalist or historical conflict, particularly in Japan's Japanese history textbook controversies.
The Empire of Japan seized concessions in areas of China towards the end of the Qing Dynasty. Dissatisfaction with the settlement and the Twenty-One Demands by the Imperial Japanese government led to a severe boycott of Japanese products in China in 1915. Bitterness in China persists over the Second Sino-Japanese War and Japan's post-war actions. This sentiment may also be at least to some extent influenced by issues related to Chinese people in Japan. According to a 2014 BBC World Service Poll, mainland Chinese people hold the largest anti-Japanese sentiment in the world, with 90% of Chinese people viewing Japan's influence negatively, and 5% expressing a positive view. Anti-Japanese sentiment in China was at its highest in 2014 since the poll was first conducted in 2006 and was up 16 percent over the previous year.
Most reasons for anti-Japanese sentiment in China can be directly traced to the Second Sino-Japanese War, which was one theatre of World War II. As a consequence of the war, China suffered 7 million to 16 million civilian deaths and 3 million military casualties. In addition, the war caused an estimated $383.3 billion USD in damage and created 95 million refugees. Manchuria came under Japanese control in 1931 as a state named Manchukuo. Many major cities thereafter, including Nanjing, Shanghai, and Beijing were occupied in 1937 by the Japanese. Notable incidents included the Nanking Massacre. In Manchuria, Unit 731, a medical unit of the Japanese army, researched biological warfare using Chinese civilians as test subjects, who were referred to as human 'logs' in the medical journals. Women from many Asian countries, including China, were made to serve as prostitutes in military brothels (and were often referred to as "comfort women") under Japanese occupation.