Sei's place was a little bit disappointing for our short stay.
It wasn't as close to Shinjuku as we had expected. Also, the "King Sized Bed" is basically two twin beds next to each other.
The building is older than other airbnb places we've stayed at in Japan, and it shows with the strange bathroom setup. You literally have to turn a crank to light up the gas water heater for the shower.
She's pretty strict about check out times. And although the description says you can leave luggage after check-out, it's not really in a secure area.

The apartment was clean. It was within walking distance of the Jujo street market area.