This unit is located in Shin Okubo, which is one stop away from Shinjuku Station. Also when I was there, Shin Okubo station doesn't have elevator or escalator. For those with heavy luggages, lot of luggages or baby stroller, please consider this.
A lot of Korean restaurant around, with nice and good food, so you won't be hungry at all.
Check with Ichimaru if the unit is occupied before you check in, I have the privilege to check in earlier as there was no guest previous day.
Ask anything from Ichimaru and you will get the most helpful tips.