Imagine every child's dream of a perfect mother. She's beautiful, gentle, and kind. She never gets mad at you. And she protects you from everything. That's Naomi's mom. We don't know if she's that perfect for real, or simply because Naomi's memories of her are rose-colored. But either way, she's the archetype of motherhood. Pretty good for someone who's been missing for most of the novel.
If there is one word constantly associated with Naomi's mom, it's "yasashii." This is how Obasan talks about her:
"Yasashi desho," Obasan says. She has often spoken of my mother's "yasashi kokoro," her tender, kind, and thoughtful heart. (8.29)
A person who is yasashii is kind of like Snow White. They are gentle, kind, sweet, and you can imagine them speaking in the same kind of lilting voice, and singing to animals. That's Naomi's mom.
For example, how would your mom react if you took baby chicks and put them into a hen's cage… and then the evil serial killer hen killed the poor, defenseless chicks? Probably not like this:
"It was not good, was it?" Mother says. "Yoku nakatta ne." Three words. Good, negation of good in the past tense, agreement with statement. It is not a language that promotes hysteria. There is no blame or pity. I am not responsible. The hen is not responsible. (11.20)
No blame. Just calm. It's this attitude that makes Naomi feel like she can tell her mom anything.
It's telling that Naomi talks about her feelings for her mother this way:
She makes safe the small stirrings underfoot and in the shadows. Physically, the sensation is not in the region of the heart, but in the belly. (11.8)
In Western culture, feelings are in the heart. But in Japanese culture, you could say that your stomach is your 6th sense (no, not the creepy "I see dead people" kind, you sickos). It might sound a little weird, but the Japanese saying translates to something like "there is a worm in your stomach."
If you instantly like someone or instantly hate someone without a reason, it's because of the worm in your stomach. So when Naomi says that the feeling she has for her mother is in her stomach, what she's really saying is that the comfort and love she provides are so profound that it is without reason.
Whoa man, that's some deep love right there.
But Mother's yasashii nature isn't all about saving baby chickens and looking beautiful. Sometimes it's hard being yasashii. Mother's kind nature takes a dark turn after we learn what happened to her in Nagasaki.
There is a huge gap of our knowledge about Naomi's mom. We see her when Naomi is a kid, she disappears, and we don't learn anything new about her until the end of the book.
What we learn is that she was a survivor of the Nagasaki bombing. Grandma Kato writes:
The woman was utterly disfigured. Her nose and one cheek were almost gone. Great wounds and pustules covered her entire face and body. She was completely bald. She sat in a cloud of flies and maggots wriggled among her wounds. As Grandma watched her, the woman gave her a vacant gaze, then let out a cry. It was my mother. (37.31)
That's what happens to Naomi's yasashii mother, her beautiful face is destroyed.
We learn that she didn't want her kids to know what happened. She says: "Do not tell Stephen and Naomi… I am praying that they may never know" (38.2). Those words would become a whole lifetime of confusion for Stephen and Naomi.
It might seem ridiculous and stupid for her to keep the truth away from them, but think about the one thing we know about Naomi's mom. She's yasashii. Gentle, soft, kind. She wouldn't want to bring any hardship into her children's lives. Think about it, what little kid wouldn't have nightmares knowing that their mom's face had been blown off? We're kind of freaked out just reading about it.
So even though the silence about Naomi's mom seems cruel for the majority of the novel, we see everything in a different light after the letter. The silence of Naomi's mom was an act of love. Even in death, she was yasashii.