Not sure what's wrong with that? That looks pretty amazing actually. I live in a unit that looks similar to that near downtown Chicago. My unit is north facing, and even so, there's more than enough sunlight.
Obviously there's nothing wrong with an apartment or microhouse, but it makes the quoted rent less impressive.
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.
I live in a pretty well to do family oriented neighborhood in central Tokyo, and this is a very common design. Although I’m not sure about mortgages, but rents definitely ain’t just $850. But as the parent post said, it’s all about location. Prices nosedive once you leave the center of Tokyo or are off the main train lines.