Inti Creates released the 4th Azure Striker Gunvolt 2 Nintendo 3DS theme what you can buy and download from the Japan Nintendo eShop.
The theme costs 150 Yen (with tax) and comes with sound effects, with the short version of the in-game song (蒼き雷霆 ガンヴォルト 爪 RoRo ♪大祓) and based on the Cyber Diva character. In the gallery you can find the sample pictures. The theme available in 2 different designs. If you buy both of them you have to pay 300 Yen (with tax).