Seiji was a phenomenal host! He met us at the apartment for check-in to show us everything. He even came out to dinner with us when we arrived, and showed us some nearby sights, like the Golden Gai drinking alley and a local shrine.
The apartment was spacious by Tokyo standards and very comfortable. We were just two of us, but one or two more people would have been fine there if they didn't need much privacy.
Everything was very clean and the apartment guide was super thorough. The bed was definitely firm (which is the preference in Japan, as we understand it), warm and comfortable. Seiji provided excellent amenities like portable wifi, towels, laundry detergent (there's a clothes washer!) and nice shampoos, face soap, toothpaste, facial toner, etc. The shower was clean and spacious, and there was a Japanese washlet toilet! Yay!
The neighborhood was great - about a 10-15 minute walk to the big Shinjuku station. (There's a smaller station nearby, but we always just got off at Shinjuku.) The area is very near great stuff -- Golden Gai, Isetan Mall, a Starbucks a few blocks away for those inclined. There's even a tiny tiny little bar (I mean REALLY TINY, like four counter seats and that's it) on the first floor of Seiji's building, and a cute German restaurant on the same street.
In general we can't recommend this apartment enough. We loved it there and will definitely be back if we return to Tokyo and it's available! Thanks, Seiji!