This was a last minute trip, so I could not book ahead. I wanted to stay in Shinjuku in a capsule hostel with a sento. Although Capsule Inn Otsuka is not Shinjuku, it was close enough. Despite the language barrier, the staff was very helpful and got me clued-in and squared away from the start. (Thank you, Ariel!)
The hostel is very clean - especially the sento. New sheets and pillow cases every day and as many towels as you need plus shampoo, condition, muse, shaving cream, razors, skin creams, after shave, etc. There is also a washer and dryer. Packing my luggage every day and putting it in a provided locker and/or secured storage area was a little annoying, but this policy allows the hostel to perform a thorough cleaning every day. Otherwise, the odor of dirty laundry within the capsules would make it unpleasant for all. Due to poor venting (inherent to older buildings), there is an odor in the restroom in the early morning.
Currently, women do not have access to the sento. Also, on the same floor as the sento, there is a common room with television, smoke rooms, and complementary coffee, but no water dispenser. Drinking water is taken from the sinks near the restrooms. If hot tubs are not your cup of tea, there are 2 regular showers next to the sento.
I enjoyed my stay at the Capsule Inn Otsuka and thank the hostel and staff for making it enjoyable.