What are the motifs in The Samurai's Garden by Gail Tsukiyama?

Loyalty is second nature to some people in Stephen's life, though his own loyalty comes into question. Stephen loves his parents and younger sister, but has also come to love his life in Japan. As he learns of the advance of the Japanese Imperial Army into China, he feels that he should be at home, but he doesn't want to leave Tarumi. He does say on several occasions that he's willing to go home, but is always relieved when he doesn't yet have to. Stephen feels the need to tell his Japanese friend, Sachi, that he will never hate her, despite the fact that the Chinese and Japanese are at war and that some will hate simply because of ethnicity.