Tokyo-based online game publisher Nexon saw its earnings for the second fiscal quarter skyrocket, thanks mainly to surging mobile game sales in China, Korea and Japan.

The company saw its mobile game revenues jump to 7.3 billion yen ($75.6 million), up from 180 million yen ($1.9 million) year-over-year -- an increase of 40.5 times. PC game revenues were also up year-over-year.

The most notable jumps in sales came from Japan and China, where Nexon says mobile game sales are exceeding expectations. In Japan, for example, Three Kingdoms Guild Battle and Euro Club Team Soccer Best Eleven+ both saw record peak revenues for the company.

Sales in North America and Europe weren't so hot -- in fact, U.S. revenues were down 5 percent year-over-year. However, Nexon notes that it has made "strategic investments" in two U.S. studios, Rumble Entertainment and Brian Reynold's SecretNewCo, and plans to build games that will be compelling to Western players.

For the second quarter ended June 20, 2013, Nexon recorded revenues of 36.6 billion yen ($379.8 million), up 60 percent year-over-year, and profits of 11.4 billion yen ($117.9 million), up 54 percent year-over-year.