Only 811,604 babies were born in Japan in 2021, almost 30,000 less than 2020. On the other hand, because of Japan's aging population, 1.44 million people died, the highest number since World War II. That means Japan's population has dropped by almost 630,000 people in a single year.
From Japan Today:
According to the health ministry, which began collecting such data in 1899, the average number of children a woman is estimated to bear in her lifetime declined by 0.03 point from 2020 to 1.30, while the number of marriages decreased by 24,391 to 501,116, the fewest in the postwar era.
The Ministry of Health, Labor and Welfare attributed the decline in newborns to a fall among those in their 20s giving birth, though it is not clear whether factors such as increasing economic insecurity or uncertainty about the future, brought on by the coronavirus pandemic, caused the decline.
Births have been on a downward trend since peaking at 2.09 million in 1973 in the middle of the country's second baby boom.