The highest birthrate in Japan is in Okinawa, almost twice as high as in Tokyo. By mysterious coincidence, Okinawa also ranks highest in happiness while Tokyo is ranked second lowest in happiness. And the two rates correlate well across the country: happier = more kids.
However, nb, it is quite possible the correlation is the other way around, the difference in birth rate is much higher (almost twice) than the difference in happiness (not very large), between Okinawa and the Tokyo/Kanto region.
Another fun correlation is between commuting times and happiness. Here the industrial/financial regions really come out poorly with the average person commuting almost twice as much as the happier more fertile regions.
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