According to a report from the Mobile Content Forum in Japan (as translated by Dr. Serkan Toto), the market for mobile gaming in that country brought in $5.1 billion in 2012. The Japanese market for mobile games has been largely based on feature phones, but smartphones are rapidly gaining market share.
Feature phones in Japan in 2012 brought in $2.4 billion, which mostly ($2 billion) from ‘social’ games distributed through networks like GREE or DeNA’s Mobage. About $410 million came from other mobile games not through those networks.
Smartphone games all told brought in $2.7 billion, showing over five-fold growth in the last year to surpass feature phone game revenue for the first time. Overall, mobile content in Japan (including games) generated $8.8 billion in 2012.
Source: Serkan Toto