Our family of 4 adults and 2 children recently spent 4 nights at Lei's house and our stay was very comfortable. When we arrived, we were able to enter the house with no problem and the clear instructions booklet really helped us figure out how to go about using the equipment in the house, as well as provide an insight into how a typical Japanese household operates.
We had everything we needed in the house: the washing machine worked perfectly (with enough detergent available), heating throughout the house was was sufficient, the full bathroom and 2 separate toilets made sure nobody had to wait in line in the middle of the night and the kitchen was well equipped.
The area is great too; it's close to a train station (Shin Okubo, just one station away from Shinjuku station and Okubo) and being in little Korea, it is surrounded by Korean restaurants and there are plenty of places to buy groceries at. There are two big grocery stores about 10-12 minutes walk from the house, but if you don't feel like walking that much (which isn`t much really), there are numerous convenience stores nearby. It's a busy and vibrant neighbourhood, but the awesome part is that in the house you don't hear anything. One night when it wasn't too cold I turned off the heating and slept with the window slightly open, and still, no noise.
I do want to point out that besides the two Western style mattresses in the main bedroom on the ground floor, the other beds in the two other bedrooms are Japanese futon mattresses on the floor, which means that if you're used to sleeping in plush thick mattresses, you'd find the futon a little hard on the body. I read that this type of bed is actually good for your back and I appreciated my authentic Japanese sleeping experience, but on the second night I put a second futon underneath my futon (which was thankfully available), so I slept much more comfortably.
Some constructive feedback for the house are as follows. One, the pillows were very thin and I had to use my travelling neck pillow instead. Two, there were no hooks provided and it being winter, we all had jackets and a coat rack would have been great to hang those jackets when we got home, instead of leaving them on the floor. Three, I don't think there`s enough seating in the living room. There's a two-person sofa and a massage chair (which was a great touch!), so if four or five people wanted to watch TV together, some would have to sit on the floor.
I would not hesitate to book this place again next time we're in Tokyo!