Last month this column discussed how lack of city planning in the suburbs had led to an over-supply of new housing that exacerbated the well-publicized vacant-home problem. It should be noted, however, that populations in suburbs throughout Japan are declining — some slowly, others rather rapidly.

Several factors contribute to this decline, the main one being that residents who have lived in these suburbs for most of their adults lives are dying and not being replaced. Another reason is that many children who grew up in these suburbs and came of working age in the last few decades have moved out, and in many cases into the cities where they work.

According to a series of articles Atsushi Miura wrote last fall for the business magazine Toyo Keizai, the last census conducted in 2015 showed that the three prefectures surrounding Tokyo — Kanagawa, Saitama and Chiba — all lost population since the previous census in 2010 with regard to people in their 20s and 30s. In Tokyo, however, there was an increase of 356,000 people, with the bulk of that increase, 327,000, in the 23 central wards. This statistic becomes even more significant when you check the shift over the past 10 years. The 19- to 34-year-old population of the 23 wards increased by 695,000, while the total decrease of this demographic in all other prefecture that lost population was 949,000. This raises the possibility that 70 percent of Japanese people aged 19 to 34 moved to central Tokyo between 2005 and 2015.