Koichi is really a nice guy and helped us a lot on our travelling in Tokyo.
Room is extremely comfy in a very convenient location, 5 mins walk to Shinjuku Sanchome metro station or 10 mins walk to Shinjuku station. Close by are Marui men and Istan department stores. Good for shopping or dinning.
In addition, Koichi san is very considerate and would think of what you may need for your itinerary. We had very good experiences staying there and really appreciate what Koichi san had done for us.
For next trip to Tokyo, to explore Shinjuku area, Koichi's room will still be the best choice.