Really nice place and nice host. Host make an effort to pick us up from Shinjuku station and also to Haneda airport at the end of the trip. Very responsive and his English is not bad, definitely good for travellers who do not speak Japanese.
Place is very clean and nice, space wise is consider very spacious for a apartment in Japan with 2 rooms and 4 comfortable beds.
Location wise it is in between to stations(Higashi-Shinjuku & Shinjuku-San chome) and both station have got different lines to major places like Shinjuku, Shibuya and Ginza. There's a Daiso and a 24-hours supermarket within 5min walk. Opposite the supermarket is the HQ of Square Enix with a small shop and cafe which sell merchandises like Final Fantasy and Dragon Quest so it's very ideal for gaming fans.
The only down side is there is no lift in the premises but the apartment is at only at level 2 and you only need to climb a small flight of stairs to get to the apartment.
Overall it is very good place to live in for your trip in Japan and I will definitely stay in Koichi place again when I come back to Japan.