The studio is just as in the photos, and the things used, such as bed, hairdryer, shower, were of good quality, as expected in Japan. It was about 7 minutes walk to the Hatagaya station on the new Keio Line and Shinjuku Line, which seemed a bit far at first but you get used to it, and I thought it was pretty convenient. Shinjuku was just 2 stops away, which made travelling to Mt Fuji easy for us when we took bus from Shinjuku Express Bus Terminal.
I loved the hot and powerful shower head, though the bathroom was smaller than the typical hotel bathroom (that is already very small). But in the tight space, two petite girls made it work and we had a comfortable stay. Walking down the 六号通り felt safe, and the studio is in a small cluster of residential area just behind the vibrant street. Do try the みやび屋 just up the street (on your way towards the 幡ヶ谷 station) for affordable skewers and 鍋!
Mitsuko-san is a very friendly host and made sure we had everything we needed. Studio is small, but complete. She also provides a mobile wifi, but the connection was at times poor. We worked with what we had though, and it wasn't much of an issue to the both of us. Bed (even the pull out one) was comfortable and had good support. The mattress for the pull out bed had an additional futon on top of it and I had excellent sleep for all 4 nights.
I will definitely be back here again if I come back to Tokyo, as the price/quality/location/convenience ratio was unbeatable!