Mrs. Yamada, Ichiro's mother, is a staunch Japanese loyalist, to the point of creating her own internal fantasy and refusing to accept the reality of World War II. Her view is that Japan won the war, and that the U.S. is simply using propaganda to demoralize Japanese-American citizens. She, like many others, refuses to learn English and believes that there will be a Japanese boat coming to take them away. Her views on Ichiro are conflicted; on one hand, she is proud of him for refusing to fight for the U.S. against Japan, but on the other hand, he is starting to think for himself, and so he clashes with her on several occasions.
"I am proud to call you my son."
It was her way of saying that she had made him what he was and that the thing in him which made him say no to the judge and go to prison for two years was the growth of a seed planted by the mother tree and that she was the mother... because no other would have made her feel [that] pride...
(Okada, No-No Boy, Google Books)
Essentially, she feels for him an old-fashioned sense of property, that children are always the product of their parents, and that pride in the children is in fact pride in the self for having raised those children. Ichiro, having developed some of his own personality while separated from his parents, refuses to go along with her fantasies, making her even more distant and subconsciously depressed. Eventually, as the reality of the war presses in, Mrs. Yamada gives up and drowns in a bathtub out of dispair. She was happy that Ichiro did not go to war, but could not accept the true outcome, preferring her inner fantasy.