Living locally I visit devadeva fairly regularly. I am a big fan of their Yogi Burgers (although perhaps not so much the bun) and like that you can choose between potato wedges and salad (or have both) to accompany it. They overhauled their menu in 2012 and several of the different burger options unfortunately vanished but this has pushed me to explore more of their other offerings!
Although slightly pricy at 1600 yen the Deli plate is a good option if you're not in the mood for a burger - you get 2 different dishes that change daily, salad, soup and a variety of breads that will be replenished upon request.
They have a good range of veg/vegan cakes and tarts etc that change regularly, and also offer a small selection of organic/vegetarian cooking supplies and snacks.
If you are in the area (the Ghibli museum is a 20-minute walk away) definitely drop in for lunch!
Updated from previous review on Thursday January 03, 2013
Update - August 2014
Visited for the first time in a few months, and saw that the menu has been revamped since we last visited. Now you can choose between the original veggie burger or a faux-chicken burger and select your toppings. Also on the menu is a "Tofish" burger with tartare sauce which I went for. It was fine, did taste vaguely fishy but overall lacked in flavour and was a bit lost in all the sauce that was on the bun (the bun has changed, far prefer this new one!) Not sure I would order it again. The burgers now all come with chips as standard and you can add salad or soup for 200 extra.
The deli menu option has also changed slightly, the offerings no longer change daily but there are more to choose from than before.Pros: Delicious burgers, Relaxed atmosphere
Cons: A bit out the way, Slightly expensive if you add drinks/desserts