What a horrible post, missing the entire point by a mile and worse yet, misguiding everyone about the most basic facts :(
I assume you're from a western society, so I can't possibly imagine how you could have possibly reached such a conclusion. The contrast should be obvious at first glance.
The default Japanese diet is greatly more healthy than the default western diet, especially the American diet.
As a person living in the west and willing to put in some of my limited effort into eating healthy, I'm screwed. There's barely any healthy options available, I'm flooded by an ocean of awful food and it takes significant effort and cost not to drown in it.
I can't emphasize this enough, it absolutely does not matter what you can technically do or not. Defaults are what matters. By default in Japan you eat a reasonably healthy diet and walk/bike regularly. By default in America you eat fast food and drive everywhere.
By American standard, basically anything is more healthy, so that is not really a good point. Do you think Italians, French, Spain or Serbians have worse food than Japan - they do not. Researchers thought it was something in red vine, then something in blue cheese, then olive oil, then fish, etc. Maybe its about so much Iodine, that is specific to Japan. I doubt its pristine environment and unique genetics.