When you receive your assignment, read it carefully to see what is required of you, but also be on the lookout for important descriptive words. You can often find useful search terms in the prompt from your professor.
When your start out, review your search results closely. Always check the SUBJECTS to find new search terms.
You might try an alternate search after viewing the subjects above.
Japanese American*
AND
internment or concentration camp* or evacuation or relocation or incarceration
Abstracts will sometimes have helpful information and useful keywords.
The abstract gives one justification for the internment of Japanese Americans: Military necessity. You can add "military necessity" to your search if you are looking for justifications given at that time. You might also be interested in the internment of Latin American citizens in the United States during WW II.
Monument in cemetary with inscription that reads, "Monument for the Pacification of Spirits"