Excellent location a hop and a skip away from Shin Okubo station on the Yamanote line or Okubo Station on the Chuo line. 10-15 minute walk from Shinjuku station, plenty of stores, restaurants, etc around the apartment.
Apartment is a fairly standard sized Japanese 1-room studio. Travelers should note that Japan is tiny. Rooms are tiny. Everything is tiny. This size is very normal for a person living on their own. All amenities were available upon entry, and host was super quick about refilling supplies as necessary within 24 hours. Host responded in a reasonably quick manner, usually within a few hours.
This place is ideal if you're a solo traveler looking for something convenient, clean and very reasonably priced for the area.