Keita's house is around 15-minute walk from Minamidaira station which is a 40-minute ride from Shinjuku station. Quite far from the center but that's what's great about it. Authentic Japanese neighborhood. He's also always willing to drive you to/fetch you from Minamidaira station, if you mind walking.
The room is clean and spacious with A/C and balcony. Kitchen and fridge are available for everyone. One evening, we even prepared dinner together in company with some of his Japanese friends.
I hope to be back here soon :).