Mao and her team are very responsive and eager to make your stay as comfortable as possible. As with most apartments in Tokyo, this studio is very small, but it is at least modernly decorated so not too cluttered. Nevertheless, I wouldn't recommend staying for more than a couple of nights, as the bed itself is very uncomfortable. You're better off staying on a tatami mat than sleeping on this mattress/pillows.
The apartment itself is only 2 stops from Shinjuku but a bit further away from the more central areas of Tokyo than we personally would have liked. There are several Airbnb units
run by the Zens team in the building. The kitchen is virtually impossible to use, unfortunately, as there is pretty much no counter space. For those on a quick visit, this should not be an issue, as you'll likely eat out most of the time. The bathroom is very small as well--the toilet is installed crookedly to fit--but it was great to have a washing machine (no dryer so few places to hang things up).
Overall, this is one of the better-looking apartments I could find on Airbnb, but I would probably look at staying in a share-house before I stayed here again, primarily because the bed was so uncomfortable. I am sure some of other apartments that are part of the Zens collection are better.