Board Thread:News and Announcements/@comment-5824377-20140328120715

Looks like files for 4 new characters were found on the game's data, as potential DLC characters.

3 Characters as Playable includes JOTARO and DIO (from Jojo's) and Dai (from Dragonquest/Fly). And 1 for Support, being Yoh Asakura (from Shaman King)

http://www.yareyaredaze.com/2014/03/28/j-stars-victory-vs-jotarodiodaiyoh-files-found/

If ths is true, Jojo will have the same ammout of playable characters as One Piece, that's badass if you ask me. 