We're nearing the release of Azure Striker Gunvolt on 3DS soon, and Mighty No. 9 is quite a ways off, but developer Inti Creates may have another project up their sleeve. According to a leak from Famitsu, there is a new crossover game in the works called Mighty Gunvolt. The game is reportedly a mixture of characters from Azure Striker Gunvolt, Mighty No. 9, and Gal Gun.
Apparently it will be a downloadable game for the 3DS, and will feature the titular characters from all three games, as well as an "80s graphic design." The official Gunvolt Twitter account has confirmed "a leak," and will have news to deliver soon -- although it isn't clear how much of the leak is true.
I've been playing Azure Striker Gunvolt quite a bit this week, and will have some more concrete thoughts closer to launch.
Report: Mighty No. 9 x Gunvolt x Galgun Collaboration Announced For 3DS [Siliconera]