Our guest were very friendly and flexible for the check-in time. As the other hosts said, the neighborhood is quite noisy but we knew it and our host mentioned it too. So it was okay for us.
But the apartment needs some more equipments like a sponge and dishwashing liquid, spoons, forks, chopsticks and some plates to eat would have been quite useful.
The neighborhood of Nakano is living and a good place to drink a beer with skewers and make shopping. The Nakano station is three stops from Shinjuku which is very convenient. We had a pleasant stay in this apartment.