Foreign publishers are still finding it difficult to break into the lucrative games markets of Japan and South Korea, according to the latest figures from the App Annie Index.

In Japan, the analytics firm found that of the 24 top grossing games in Japan during May – across both iOS App Store and Google Play – 21 were published by Japanese companies.

The most successful foreign games were Megapolis (published by Russia’s Social Quantum), Iron Man 3 (Gameloft, France) and Master of Chaos (Koramgame, China).

Japan’s LINE dominated the May rankings, along with GungHo Online (primarily for Puzzle & Dragons) and COLOPL.

In South Korea, just 7 of the 27 unique games covered by the App Annie Index in May hailed from overseas. In the iOS rankings (by downloads) the only foreign publishers to make the top ten were from France (Gameloft), China (com.digitalcloud) and the US (Kabam).

On Google Play (measured by revenue) South Korean publishers occupied all top ten positions.