This is the real answer. Japanese tax law heavily incentivizes building and discourages sitting on land forever and doing nothing with it for one’s own investme

This is the real answer. Japanese tax law heavily incentivizes building and discourages sitting on land forever and doing nothing with it for one’s own investments (paging California). Helps that the whole country is on a fault line; nothing is going to stand up for a while anyways so you may as well establish a culture of rebuilding.