On 3DS
Kaku-San-Sei Million Arthur is a popular card battle game in Japan. Originally it was on iOS and Android, but the original smartphone version was eventually dropped in favor of keeping up the 3DS and Vita editions.
On 3DS, developer Square Enix is offering up a cross-promotional event involving Bravely Second characters. Multiple heroes and enemies will show up, which you can view in the gallery below.
Bravely Second Characters Dive Into Million Arthur On 3DS [Siliconera]