We (family of four) stayed at Masami's apartment for 5 days and found everything as advertised. The excellent reviews that Masami has are certainly warranted! The apartment is very comfortable, even for four people, clean, well equipped, the directions and instructions are very useful, and Masami has been a great host; she is easy to communicate with, responds quickly and very helpful - we even could check in early as no other quests were in the apartment the day before, which was much welcomed after a long overnight flight from Europe.
What we particularly liked was the location of the apartment. There are plenty of nice and authentic restaurants around the corner, a supermarket as well as convenient stores where you can restock on food are a couple of minutes away, and a stop for the Keio New Line is also around the corner. From there it is just two short stops to Shinjuku Station, so you can reach nearly any place in Tokyo easily.
All in all a wonderful stay and we already booked our next stay with Masami!