I went both to the Kunitachi and the Roppongi location. The Kunitachi restaurant's interiors are not as nice as the one in Roppongi, but the food is just as delicious and it is not so crowded. I ordered the Spring Roles, Ebi Fry and Taiwanese Beer, all very good. I will definitely eat there again. Most of the food is vegan, there are only a few non-vegan meals and they are clearly marked on the menu. The restaurant is not very hard to find as the entrance is from the main street and there are signs (also in English). You should look for 台湾 (or was it 臺灣 ?) on the window.
Updated from previous review on Sunday November 30, 2014
Ordered snowfish the other day and it was delicious!
Updated from previous review on Saturday December 13, 2014
Edit: Menu has changed, remember to double check whether your dish is vegan!