Japan’s Mobile Content Forum (MCF), an industry association, just reported that Japan’s market size for mobile games has reached the equivalent of US$12 billion in 2021.
(Due to the recent and drastic yen-dollar currency fluctuation*, the sum in US$ is smaller than last year.)
The growth rate is not as high as in the year prior, probably because of diminishing corona virus effects:
*Currency conversion as of July 30, 2022 Japan time: 100 yen = US$0.75.