Great place to stay. Very central with lots around. Take the higashi-shinjuku station for the closest train but yamonote line not that far either.
The elevator is on the second floor after a steep narrow flight of staurs which was difficult for our luggage. The windows are very thin so you can hear everything outside which gets pretty loud since it is centralized ktown. The place is kinda dusty maybe from the large closet? And the bed was kinda uncomfortable. There was work going on in the building both upstairs and downstairs so we were awoken several times. Other than that we actually love the place. Its not the owners fault regarding construction and loud area but thats what you expect with a busy area. Spacious and the washroom was spacious for a city apartment. Owner was super nice and super understanding and replied very quickly. Would definitely stay here again if we wdidnt have lots of luggage.