Pardon me, but I don't get how this is supposed to be a seiyuu joke. Kallen's not wearing Yukiko's uniform from Persona 4, and to my knowledge none of these character's voice actors (with the exception of Koshimizu Ami) appear in each other's series.
Maybe this should just be in the "crossover" tag instead? The artist did start to draw Persona 4 doujinshi after spending a long time with Code Geass and the Euphemia/Suzaku pairing.
