This pleasant stay comes at a small price. To start, the location is conveniently next to the Nishinippori JR Station. That is super useful for foreign travelers to Japan. You are a 2 minute walk from the Yamanote Line. You can go pretty much anywhere in Tokyo with that train line. Keep in mind, train noise is certainly noticeable from the airbnb.
The space is small, cozy, but a little tight, especially in the bathroom. The toilet is so close to the door, I hit my head on the door trying to sit on the toilet. The shower space/sink occupy the same square feet as the toilet space but that part was fine for me. It was difficult to dry and change close in the dry areas of the bathroom.
Lastly, the bottom bed is 5x more comfortable than the top bed. The stay will be ore pleasant for those not in the too bunk. Maybe a thicker pad could be used for the top bunk to make that more comfortable.
Overall, as a bottom-bunker, I had a fine stay at this airbnb. The train noise made for a decent alarm but i got used to it the longer I stayed.