Developer Examu is renowned for creating the Arcana Hearts trilogy, a series of fighting games with an all-female cast that also features the Arcana system, which determines the cast's special moves. The developer is currently collaborating with Aquaplus to create AquaPazza, a 2D arcade crossover fighting game that features characters from Aquaplus visual novels, as well as a tag-team battle system.
The entire cast is probably alien to you unless you've read an Aquaplus novel.
Aquaplus recently stated on its blog that the game will be out in Japanese arcades in the middle of June. The characters confirmed so far in the game are Multi from To Heart, Tamaki Kosaka and Manaka Komaki from To Heart 2, Arawn from Tears to Tiara, and Touka, Hakuowlo, and Karulau from Utawarerumono.