One thing about Japan is that you'll find the best chefs of all types of cuisine. That means that, yes, you can find good italian in the middle of Tokyo.
Trattoria Tavolo di Fiori is no Michelin rated restaurant; but they made a good go of it for sure. I was very pleased with its discrete wine, and al-dente prepared pasta. I'm glad I wandered into this place instead of just walking by.