We love Japanese food so having what looked like an authentic restaurant in our hotel lobby was very handy. Lucky for us it was also great food and service.
The staff are Japanese and speak it a lot, especially if they think you do too (I do only a little). The menu mat need a little explaining if you're not familiar with Japanese meals.
The udon was delicious, the salad dressing was home made, and the yaki tori sauce was amazing.
There also seemed to be locals eating there, which is a good sign for a tourist hotel restaurant!
I'd highly recommend this one if you'd like a Japanese meal whilst in Waikiki.