Yohei Maruyama: What the Population Influx and Single-ization of Tokyo's Special Wards Suggest

In April 2024, Toyo Keizai Inc. published "The Shock of Middle-Age Singles in Tokyo: The Future of a 'Solo' Society." The middle-age period refers to those aged 35 to 64, an age group previously assumed to naturally marry and form families, but which is now seeing an increase in single individuals. This book focuses on the fact that this trend toward middle-age single-ization is particularly prominent in Tokyo's special wards. It analyzes the reasons and social impacts, attempting to propose a framework for the challenges we must address moving forward. As a co-author, I was responsible for Chapter 2, "Migration to Tokyo's Special Wards and Single-ization," from the perspective of population movement. Since publication, I am grateful that the book has been featured in various media through book reviews and other outlets, which led to this writing opportunity.

The starting point for the research on middle-age singles in this book was a three-year study on the lives of single residents conducted starting in fiscal 2013 at the Shinjuku City Autonomous Creation Research Institute (Shinjuku City Hall). I was involved as a part-time researcher, having just completed the coursework for my Doctoral Programs. While the increase in elderly singles was recognized as a social issue, the fact that middle-age singles were also significantly increasing was largely overlooked, as they were generally perceived as a generation with few problems. In this context, Shinjuku City had a strong sense of urgency because the single rate among its middle-age population was exceptionally high nationwide, and these individuals would eventually become elderly singles as they aged. A survey was conducted to clarify their actual living conditions. As a result, the diverse realities of middle-age singles in the central Tokyo area of Shinjuku were brought to light. It also became clear that there is a segment requiring urgent support in terms of economic risk and the risk of social isolation.

Following this research in Shinjuku, in order to capture the living conditions of middle-age singles across the broader Tokyo special wards, a two-year research project titled "Analysis of Small-Area Population and Households in Special Wards and the Current Status and Challenges of Prime-Age Singles" was launched at the Association of Mayors of Special Wards Research Institute starting in fiscal 2019. In addition to macro-level population and household analysis of Tokyo's special wards, we conducted awareness surveys and interviews targeting Setagaya, Toshima, and Sumida Wards. The research results, which closely examined the human relationships and daily lives of middle-age singles, led to this current publication.

Within this series of studies, I have been responsible for macro-level regional population analysis regarding the impact of population movement on the progress and prominence of single-ization in Tokyo's special wards. While Shinjuku and the other special wards continue to see a population influx from surrounding areas and regional zones, they also have low birth rates and are areas where the single-ization of the middle-age population is prominent. How these elements are interrelated is the analytical perspective I have maintained. Below, based on this viewpoint and the reality of population movement and single-ization in Tokyo's special wards, I would like to consider how these wards will transform in the future due to middle-age single-ization.

Let's look at the situation in Tokyo's special wards using specific data. To state the conclusion first, when comparing the middle-age population living in Tokyo's special wards between those from within the Tokyo metropolitan area and those from outside it, the latter has a higher single rate. This indicates that population movement between the Tokyo metropolitan area and regional areas is linked to the prominence of single-ization in Tokyo's special wards.

Calculating the middle-age single rate from the national census, the national figure in 1980 was 4.7%. As shown by the fact that it was below 5%, approximately 40 years ago, the vast majority of people in their middle-age years were married and had their own families; singles were a minority. While this single rate has been rising, the background to this is the progress of the trend toward remaining unmarried, as well as changes in family formation behavior such as later marriage or non-marriage. There are also regional differences in middle-age single-ization, which is more prominent in the Tokyo metropolitan area and Tokyo's special wards. In 1980, the rates were 4.7% nationally, 5.7% in the Tokyo metropolitan area, and 9.4% in Tokyo's special wards. By 2020, these were 15.8%, 19.1%, and 27.5%, respectively, representing increases of 11.1, 13.4, and 18.1 percentage points over 40 years. It is clear that the middle-age single rate in Tokyo's special wards is at an overwhelmingly high level even when looking at chronological changes.

Why has middle-age single-ization become so prominent in Tokyo's special wards? Let's consider this in relation to population movement. Driven by a large net migration gain, the population of Tokyo's special wards continues to increase. However, changes have occurred in the age patterns of this net migration. Until around the bubble economy era, the age pattern for Tokyo's special wards and the Tokyo metropolitan area showed a net influx from the late teens to early 20s, followed by a net outflux from the late 20s onwards. The former reflected migration for education or employment, while the latter reflected return migration such as "U-turns." However, entering the 21st century, the net influx has continued into the 30s and beyond, and the trend of the middle-age population concentrating in Tokyo's special wards and the Tokyo metropolitan area has intensified. This has also become the pattern of population movement driving the recent "return to the city center" trend.

What I considered here is the relationship where, among the middle-age population living in Tokyo's special wards, those from outside the Tokyo metropolitan area have a higher single rate than those from within it—a hypothesis that population movement promotes single-ization. There is a wealth of international research on the relationship between migration experience and family formation behavior, and in Japan, it has been clarified that those with experience moving to major metropolitan areas have lower birth rates or higher lifetime non-marriage rates. I thought the same framework could be applied to middle-age single-ization.

To clarify this relationship, I combined the results of the Migration Survey by the National Institute of Population and Social Security Research with the national census to estimate the single rate of the middle-age population living in Tokyo's special wards, categorized by those from within and outside the Tokyo metropolitan area. Unfortunately, since the Migration Survey data is only available at the prefectural level, I substituted Tokyo Metropolis data for the situation in Tokyo's special wards.

Figure 1 shows the results. For both men and women, the single rate for those from outside the Tokyo metropolitan area was higher than for those from within it. In other words, the population group that moves from outside the Tokyo metropolitan area to Tokyo's special wards and contributes to the return to the city center has the effect of promoting the single-ization of Tokyo as a whole. For the six points in time where data could be estimated, the gap in the single rate based on place of origin was 4.3 to 11.1 percentage points for men and 0.9 to 3.1 percentage points for women, showing that the gap is larger for men. Men also have a higher overall level of singlehood, meaning that the effect of migrants from outside the Tokyo metropolitan area raising the single rate of Tokyo is significant.

I would like to consider the fact that middle-age populations moving from outside the Tokyo metropolitan area are becoming more single from the perspective of life course diversity. Modern society is one of increasing diversity. Living alone in middle age can be seen as one result of a diversified life course. While it may not necessarily be the life course one imagined, it also means we are no longer a society forced into the uniform family formation known as the "standard family" (a salaryman husband, a stay-at-home wife, and two children).

Uniform life courses, especially those with strong traditional norms, still have relative remnants in regional areas, particularly those that can be described as "the countryside." Perhaps the meaning of escaping from negative images, such as a gendered division of labor consciousness close to sexism, has come to be more strongly reflected in population movement from regional areas to Tokyo's special wards. I believe that people attempting such moves are thinking of breaking away from uniformity and thirsting for diversity, with the hope that an environment that tolerates diversity exists more in major metropolitan areas—especially Tokyo's special wards—than in regional areas.

However, the tolerance for diversity in major metropolitan areas is only relatively high and cannot necessarily be said to have reached a necessary and sufficient level. This is evident, for example, in recent discussions on work-life balance and remote work, or discussions on gender and sexuality. Nevertheless, if it is "better" than in regional areas, the influx of population into the Tokyo metropolitan area and Tokyo's special wards will continue, and the living realities of the single segment will likely diversify even further accordingly.

Into what kind of region will Tokyo's special wards, with their many middle-age singles, transform? First, there will likely be a further increase in middle-age singles who do not have families in the future and are prone to social isolation. Furthermore, some of them may be placed in unstable economic situations due to non-regular employment, potentially giving rise to a new underclass. If such people reach old age, Tokyo's special wards might turn into places where people living precarious lives reside together.

On the other hand, if we view the increase in middle-age and elderly singles positively and can create various services for singles through public-private collaboration, there is a possibility that Tokyo's special wards could lead the way as single-friendly regions. If it becomes a place where people can enjoy the freedom to actively choose to be single rather than not choosing marriage, it will likely become a society that broadly and deeply tolerates diversity in its formation process. This might lead to further single-ization of those from within the Tokyo metropolitan area and an increase in the influx of singles from outside the area.

In any case, it is certain that middle-age singles will increase nationwide, and Tokyo's special wards will likely become a place that constantly faces the new social challenges brought by singles and seeks answers to them.