The place is absolutely charming, staff very helpful, and one of the girls that work there is definitely the nicest and cutest person I've ever met (and as I'm living in Japan, it's saying something!). Food is perhaps the best I've eaten in Japan. If you don't have time to eat in the cafe, just grab your bento box during the lunch time or a Loving Burger in the evening.
To get to this cafe, get off Marunouchi line in Yotsuya-sanchome, take exit number 4 and go straight till the first left turn.