Quick review to thank Hiro for his hospitality, his kindness and his good tips.
The room is simple and confortable, futons are nice and soft. There's a balcony to enjoy. The area is the absolute best...you don't really need Shinjuku or Shibuya when you have you have Koenji. Still, the place is a seven minute walk to the station and two stops away from Shinjuku on the Chuo Line.
Great stay.
Thanks Hiro