Galen Merriam Fisher was one of the few White American activists protesting for the civil rights of Japanese Americans during World War II. Japan's attack on Pearl Harbor brought the United States into World War II in December 1941. Prioritizing national security, President Franklin D. Roosevelt issued the Executive Order 9066 in February 1942. It called for the exile of Japanese Americans to incarceration camps without trials or hearings, where they experienced racial discrimination, prejudice, and unequal treatment. This article examines Fisher's activism on behalf of Japanese Americans. As a former long-time missionary in Japan, he consistently voiced his concerns about maltreatment of Japanese Americans to the U.S. federal authorities and the public. While offering detailed historical context, this study carefully analyzes Fisher's arguments about the violation of constitutional rights, harsh treatment, and racial discrimination at the camps, and for early release of Japanese Americans. It will support historians, Asianists, and scholars of Asian American studies because it offers a model to advocate against injustices and for civil rights, which one can apply to other similar historical and/or current contexts.