The Zens team that manages this apartment was very responsive during our stay, no matter the time of day they responded within 30 mins. The apartment itself is super cute and looks just like the pictures. One of the best parts was the double pane windows that completely blocked out the city noise!
It is a short 2 min walk to the Shinjukugyoen-Mae Station (Metro subway) and a 15min walk to the JR station. Also, it's right above a pub style bar with good beer, and many restaurants.
Would stay here again.