Very spacious room for two people. I can definitely see this place being a kids-friendly house. My wife and I stayed one night, however the nearby expressway was too noisy for my wife (the building even shakes a little when a large truck drives by). For me, I can sleep through it and it didn't bother me. We ended up "giving" the room to my mom, who happen to also be in Japan, while we booked a new, quieter stay.
So, overall it's a spacious place, but not good for noise sensitive sleepers.