I have been to all three of the Chaya Macrobiotics restaurants and I have to say I think they are some of the best restaurants in Tokyo. They really understand vegan substitutions (unlike many Japanese restaurants) and their vegan desserts are to die for!
The only non-vegan items on their menu are fish (since it's a macrobiotic place).
If you're looking for a place with American- or European-type food with a Japanese flair, look no further! They also have some nice packaged snacks and treats that you can buy for the road.
This particular location in Hibiya is a nice lunch spot and is close to the train station.