Audience-Alienating Premise: Lampshaded in many reviews. On paper, a musical about WWII and the internment of Japanese-Americans would sound like a terrible premise, but it works.
Some Anvils Need to Be Dropped: The WWII-era bigotry and discrimination against Japanese-Americans was wrong, and Japanese-Americans were still Americans nonetheless. Overlaps with Values Resonance as well, since around the same time the play premiered, bigotry against American Muslims hit a level unsurpassed since the September 11th attacks, as many politicians seriously proposed cataloging or interning American Muslims as well as Middle Eastern Americans.
It doesn't help that a lot of people LITERALLY invoked the Japanese-American camps as a good idea to handle Muslims, despite almost everyone considering the camps such a shameful part of American history that it isn't even mentioned in most schools.
Tearjerker: Many moments, but the clincher is the fact that Sam's father kept the Life magazine photo of his son and Kei gives him back the purple heart. It's hugely symbolic of them reconciling their bitter disagreements of how to cope with their terrible situation America placed them in, with the Americanized Sam believing it's right to keep fighting for America and Kei and her husband being more openly resistant to America.