Coming of Age Day

Coming-of-Age Day falls on the second Monday of January. It celebrates young people becoming adults and living on their own terms. The Statistics Bureau, Ministry of Internal Affairs and Communications, known as SBJ, publishes an annual new adult estimate for January 1.

The figure uses Population Estimates, the admin data system built on the Population Census, with no sample survey. It covers usual residents including foreigners and excludes diplomatic, consular and military families. The series runs since 1968, and SBJ plays the central role in producing and sharing basic official statistics.

The target is age 20 until 2022, ages 18, 19 and 20 together in 2023, and age 18 from 2024. The Civil Code cut adulthood from 20 to 18 in April 2022 with transitional measures. It is not an economic gauge, a ceremony headcount or a cohort forecast, and the publisher gives no trading signal.

The reference date is January 1 of the new adult year. The vehicle is the annual News Bulletin item with no stated time or time zone. Each issue carries NEWS HIGHLIGHTS with MAJOR INDICATORS links.

Monthly estimates refer to the first of each month and appear by month end. Annual detail as of October 1 appears in April. The 2020 Census base runs back to October 1, 2020, with intercensal adjustment between censuses.

Finals settle five months later on updated sources. Early inputs reuse older data, then preliminary reports. No exceptions are stated.

The total moves with five admin parts that join into one age. There is no threshold, boom line or 50 mark.

• Base population: the complete Census count that anchors later adds, now the 2020 Census rolled forward from the prior October 1.
• Natural change: live births minus deaths from Vital Statistics of the Ministry of Health, Labour and Welfare.
• External migration change: entries minus exits from Statistics on Legal Migrants, excluding stays under 3 months.
• Nationality net change: acquisitions minus losses for Japanese only from gazette notices and Ministry of Justice data.
• Inter-prefectural net migration: in-migrants minus out-migrants for prefecture estimates only from Basic Resident Registration.

The new adult population on January 1, 2025 was 1.09 million, up 0.03 million from the previous year. Males were 0.56 million and females 0.53 million, a gap of 0.03 million. The sex ratio was 105.2 males per 100 females. The share of total population was 0.88%, up 0.02 points.

The publisher tied the rise to higher births in 2006 than in 2005. Headlines thus follow births 18 years earlier. The series began in 1968 and peaked at 2.46 million, or 2.40%, in 1970. That peak matched the first baby boom in 1947 to 1949.

It reached 2.07 million in 1994 with the second baby boom in 1971 to 1974. It has fallen since 1995, so the rise looks small inside a long decline.

1. Base population: Start from the most recent complete Census count, then the prior October 1 final estimate.
2. Natural change: Add live births minus deaths from Vital Statistics, apportioning unknown age deaths by known shares.
3. Migration change: Add entries minus exits from Statistics on Legal Migrants, excluding stays under 3 months, plus prefecture nets for prefectures only.
4. Nationality net: Add acquisitions minus losses of Japanese nationality for Japanese only from gazette and Ministry of Justice data.
5. Aggregate and seasonal stability: Sum single year results into published age groups and take the target age on January 1 with no stated seasonal adjustment.

Short stays under 3 months stay out, keeping results seasonally stable. For example, 100,000 plus a natural net of 300 plus a migration net of 100 plus a nationality net of 50 equals 100,450 nationally. With a prefecture net of 30, the total is 100,480.