I come back to Japan once a year, and Koichi-san's place was one of the best, regardling the location, hospitality, amenities, and the value for the cost.
I used to live in Tokyo, and I have chosen Koichi-san's place as I knew the area is very convenient to go anywhere and the best place for shopping. Koichi-san's place is in a walking disance from Shinjuku Station, but at the same time, is located in a very quiet residential area.
Koichi-san was very kind to pick me up from/to the Shinjuku station, which was really helpful as I had heavy luggages.
The apartment has all the amenities you would need for a long stay, and Koichi-san is very responsive to all the messages.
It was really a pleasant stay. Highly recommended!