We stayed in two of Masami's apartments and they were both fantastic Airbnbs, easily the best of the several we stayed in whilst in Japan. Extremely clean, very organised with a lot of effort and special touches put into them. Masami is a great host, responds quickly and is helpful and flexible. Great location, a quiet residential area but very central being so close to Shinjuku. Definite recommend! This apartment was big enough for us as a couple with a suitcase each :)