A Taiwanese Imperial Japan Serviceman is any Taiwanese person who served in the Imperial Japanese Army or Navy during World War II whether as a soldier, a sailor, or in another non-combat capacity. According to statistics provided by Japan's Ministry of Health, Labour and Welfare, during the Second Sino-Japanese War and the subsequent World War II, a total of 207,183 Taiwanese served in the military of Imperial Japan and 30,304 of them were declared killed or missing in action. The vast majority of Taiwanese servicemen up to 1944 were in non-combatant roles and the majority of Taiwanese combatants were deployed in Southeast Asia as Japan did not trust them to fight against mainland Chinese. Taiwanese servicemen were abandoned by Japan at the end of the war and no transportation for their return was provided. Ex-servicemen failed to obtain restitution for unpaid wages from Japan in the following decades.

In Chinese culture, the word hanjian is a pejorative term for a traitor to the Han Chinese state and, to a lesser extent, Han ethnicity. The word hanjian is distinct from the general word for traitor, which could be used for any country or ethnicity. As a Chinese term, it is a digraph of the Chinese characters for "Han" and "traitor". Han is the majority ethnic group in China; and Jian, in Chinese legal language, primarily referred to illicit sex. Implied by this term was a Han Chinese carrying on an illicit relationship with the enemy. Hanjian is often worded as "collaborator" in the West.