So far our experiences with Italian Restaurants in Japan have been nearly universally good. They are cheap and very good. Gioia Mia is no exception.
We had great antipasto, spaghetti, prawns and dessert on the set menu at lunchtime for a price of 4500 yen for two. The service was friendly and quick.
On the weekend its busy. I'd suggest you go early or late unless you like waiting. Also don't forget to bring your katakana cheat sheet. There is English or Italian text on the menu.
Its on highway 400 on the way to Shiobara. It opens at 11:00 AM and closes at 10:00PM. Its part of a chain of restaurants, normally thats a negative for me, but in this case, I'm happy there is more than one of them :-)