We didn't get to meet Koichi which was a shame, his apartment was perfect for us. It's walking distance from a few stations in the Shinjuku area and it's even closer to the Golden Gai. It's tucked away but easy to find the first time with Koichi's helpful guide.
There are a couple of tatami mats plus the 4 beds (made up of 2 bunks). With the usual amenities, we were able to wash some clothes and hang them up outside on the balcony.
Koichi had left out loads of information about Tokyo, the local area and things to do. There were also lots of helpful hints inside the apartment on how to control the air con etc.
We cannot fault Koichi's apartment, it worked for us perfectly. We would stay here again and recommend it to anyone wanting to stay local to Shinjuku/Kabukicho. The portable wifi hotspot that you can take out with you really helps when you want to look something up, or get directions.