Koichi's place is awesome.
The location is GOLD. There are convenient store and laundromat nearby. It is close to Shinjuku-Sanchome station and walkable to Shinjuku shopping/restaurants area. Kabukicho is very close but nothing scary, good place to roam and dine at night. The neighborhood is residential area.
The house itself is well equipped. Kitchen/microwave/washing machine/towel. Very comfortable place to stay. Heater helps a lot in Autumn/Winter.
Koichi, the host, is a kind, helpful and resourceful. Not only he picked us up from/to the train station, he took care of our luggage that we sent to him beforehand. He is a guru of restaurants in Shinjuku. We went to many places he recommended. They were delicious!
If I come back to Tokyo I will stay at his place again for sure. Also, I will recommend his place to my friends.