Hijiku -
I think you heard a rumor. I did a google
search, and if DDR were banned in Japan, I would expect I would have found some news story on that. I saw no results for that in the first 5 pages.
Now, with that said, you can get a bit of a work out from that game, and when someone in poor shape does a strenuous workout without appropriate preperations, injury or death are possible. (This is why you should work out regularly to stay in shape, and if you are out of shape, work up to the strenuous workout.)
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