there's lots of japanese cuisine.
it really depends on what you want to have. for sushi though, you can't go past suzuran @ camberwell, although they're takeaway only.
And then there are the izakaya sake bar style places where its kinda like a japanese style tapas place, and for that, i recommend maedaya.
And there's teppanyaki, which is pretty much a scam (LOL), i used to be a teppanyaki chef @ fuji teppanyaki, and tbh, dont go there, or any other teppanyaki restaurant for that matter.
And for hot food, you could try ash's recommendation, in fact, i will eventually go there to check it out, but i'm in no hurry.