Japanese mobile games giant DeNA likes developer Cygames so much, it’s bought a 20% stake in the company. For $92m.

The deal, which values Cygames at a startling $460m, was spawned by a profitable existing relationship between the two firms. Cygames made card-battle game Rage of Bahamut for DeNA, which has been a top-grossing success globally.

DeNA will take a slot on Cygames’ board of directors when the acquisition goes through, which is expected to happen by the end of 2012. The companies are promising to “strengthen their existing relationship by promoting further fusion of Cygames’ creativity and DeNA’s proven expertise in social game development and operation”.

Cygames also developed branded title Marvel: War of Heroes for DeNA. PocketGamer.biz notes that the game has soared up the Google Play and App Store charts faster than Rage of Bahamut did, indicating another lucrative hit.

Earlier this week, DeNA reported its Q3 financials, posting revenues of $627m and operating income of $254m.