Tokyo is in the midst of a construction boom, with old high-rise office and apartment buildings being rebuilt in more modern and elegant forms, all while maintaining stringent environmental standards. So bright is Tokyo's gleam — which is sure to impress visitors at the 2020 Olympic Games — that the city might seem like an anomaly, given gloomy reports that, after decades of stagnation, Japan's GDP growth remains anemic.

In fact, even the small cities of Kushiro and Nemuro in Hokkaido, located near the disputed islands between Russia and Japan, are being rebuilt and modernized at a brisk pace, as is apparent to any tourist (as I was this summer). What explains this divergence between disappointing national economic data and visible progress in Japanese cities?

It may be a problem of calculation. According to official data, Japan's economic growth slowed by one percentage point, in real terms, in the 2014 fiscal year. Yet, according to Bank of Japan researchers, tax data suggest that growth was more than three percentage points higher than the official figure, implying that GDP was some ¥30 trillion (about $300 billion) larger than officially reported.