I recently saw that A3! and the popular rhythm game Taiko no Tatsujin had a collaboration where several cards were released to A3! themed like characters from Taiko no Tatsujin (here's a link to a tweet from Mankai Company about it).
I know that what a bunch of games do with a collaboration when they also have international servers is that they only release the collaboration cards on the Japanese servers and nowhere else. Would this be one of those cases?