From the images and videos I have seen of Tokyo, I would say the Japanese seem to have an aversion to waste like Detroit. Much of Detroit is a wasteland.
You can Youtube “Abandoned Detroit”
You are correct . Every inch of available space is utilized . There are some very beautiful parks / spaces in Tokyo and still a few sections where you’d think you were in the countryside : quiet , green , peaceful ...But alas , they are getting scarcer as the megalopolis continues to grow .