Cynthia Guest house is a bit off the beaten path in a quiet residential area in Tokyo. Stayed there for four nights and enjoyed it very much! What a refuge from the hustle in the centre. Everything is clean, tastefully decorated (with a very nice touch!), and new. Furthermore, everything was actually much more spacious than anticipated (this being Tokyo after all)... another benefit of being a bit further out (actually close to Kichijoi and the Ghibli museum). There is a beautiful river with nice walks nearby. The host is incredibly friendly, well travelled herself, and speaks very good English.
Overall, very highly recommended if you want to get some piece and quiet, safe, clean, and very homely accomodation with a fantastic host.