In my opinion this apartment is not big enough for three people. If you have big luggage it's barely enough for two people. Since this apartment is on the 4th floor it's best to not stay there with big luggage anyway since the stairwell is quite narrow and steep. We had a lot of trouble getting them up. The apartment is quite cosy and clean, but the sofa bed is not comfortable at all. It's hard and it hurts quite a lot when you move a lot. The normal bed is totally comfortable whatsoever. And since this apartment is next to a few restaurants and a karaoke bar it can get really loud in the night.
If you travel with light baggage and prefere to be near the Hotspots in Tokyo I can totally recommend this place though!