It was not magic but wonderful and amazing engineering done by the Japanese engineers. The high old sky scraper of Japan which was used before as a hotel was first planned to be demolished but then crushing it down would affect the other buildings within its surrounding so the engineers had thought of a better way and that is to shrink the building instead silently without affecting the other buildings in its surrounding.
It was noticeable of course from the outside that the building was shrinking and most citizens thought there was magic which made it to become like that. Then there came the explanation. As per the engineers, this can be done to any other building as well in the world and that it would be a better option if there are buildings which surrounds the building which will be demolished.
So I guess the world's engineers should consider asking the Japanese engineers who was the master mind of this magic. Check the video: