Allegiance (*** out of four stars), the new musical that opened Sunday at Broadway's Longacre Theatre, is as corny as Kansas in August and as obvious as Lady Gaga on a red carpet. But darned if it won't get a grip on your heartstrings. The flawed but defiantly moving show, which marks the Broadway debut of beloved Star Trek actor and social media darling George Takei, tackles an underexplored dark chapter in our history: the internment of Japanese-Americans during World War II.