Within 2 minutes walk of exit B1 at Higashi-Shinjuku station in Shinjuku City (same side of the main road as the hotel). If you're dragging heavy luggage use the elevator at exit B2 and you'll be just across the main road from exit B1. This station (Higashi-Shinjuku station) connects you to both (brown) Fukutoshin line and (red) Oedo line.
The rooms and bathroom are tiny but bed is big and comfy. Heat kept me comfy when it's cold outside and plenty of hot water for showers. Mini fridge keeps milk, drinks, yogurt and other snacks cold and the tiny kitchen sink is nice addition to the bathroom sink.
There are no utensils so I bought disposal bowls and spoons at Welcia drug store around the corner and further down on the same side of the main road is My basket supermarket to get groceries and food.
About 1km west from the hotel (longer walk) is one of the JR metro lines at Shin-Okubo station and lots more places to eat over that way too. I would definitely stay again in this location!