Not normal for who? Because in Tokyo, the house in the pic is quite normal. If I look just from my rooftop, I can probably count 20 houses of a similar design.

Also, keep in mind the height of the house. People tend to build up here rather than wide -- at least in family areas in central Tokyo. My current house, while slender is almost obscenely tall. It's four floors including the rooftop deck. In comparison, my childhood house back in midwestern America, seems much less spacious.