Dietary fat isn't actually bad for you in reasonable amounts. It's the overindulgence of carbs, which turns into body fat.

Also the Japanese diet is interesting. It's actually not low-calorie pound-per-pound, but the portion sizes are much smaller. The Japanese just eat less than Americans.

It has also a surprisingly small amount of greens. There is usually a pickled vegetable dish on the side, but that's it.

Source for the low calorie bit? Seems unlikely, given the amount of rice consumed.

You seem to be assuming "the amount of rice consumed" is high, but are you taking into consideration that the average portion may be small?