Aneko- It's not always easy to find names from your culture that will be well-received in America. Aneko, however, would be perfect on a Japanese-American child. Her similarity to Annika and the like give Aneko a familiar feel--no mispronounciations likely. Bonus: she means "older sister," perfect if you plan to have a big family.
Haruko- Haruko is a classic Japanese name. But even though she's conventional in Japan, you'll rarely hear her around the U.S. Haruko means "Spring child" or "sun child," which would be a sweet meaning for those warmer month babies.
Kyoko- Yoko is a beautiful name, but unfortunately she's hard to use due to the heavy associations with Yoko Ono. But add one letter and you get a completely different name (though it is, in fact, the name of Yoko Ono's daughter). To stray away from Yoko even further, use alternate spelling Kyouko.
Mieko- Lovely Mieko--that's mee-ay-ko--has many many meanings. Nameberry claims she means "prosperous," while Behind the Name cites "three branch child," "three blessing child," and "beauty blessing child" as possible meanings. Either way, it's all good (and she would make a nice choice for a third child).
Naoko- You've probably noticed that many Japanese names end in the -ko suffix. In Japanese, ko means "child," hence all these names have child as a part of their meaning. As for Naoko, she means "obedient child" or "honest child," depending on how you translate it.
Nomi- I suspect Nomi will be the overall favorite of my readers. She's easy to like--it's that long o sound--but delightfully unusual. Multicultural families take note: Nomi has roots in both Hebrew and Japanese.
Sakura- Sakura is a name many people are familiar with, though not necessarily as a given name. If you're into mommy blogs, you'll probably recognize it from the sling brand Sakura Bloom. She means "cherry blossom," which begs the question: is this the perfect name for a springtime Washington D.C. baby?
Takara- Looking to honor a Tamara or Kara in an interesting way? Takara is a beautiful option. She means treasure or jewel, so unsurprisingly there are more than a few jewelry companies with the name.
Umeko- I have loved the name Umeko for ages. There's just something about her--I can't put my finger on it. Umeko means "plum child," which gives you another excuse to use one of my favorite nicknames--Plum.
Yuki- Yuki is a unisex name that most Americans are familiar with. Perhaps, then, you already know that she means "snow." However, Yuki has many possible meanings. "Happiness," "valuable reason," and "chronicled reason" are among them. Whatever meaning you decide is right for your little Yuki will be perfect.