TYPE-MOON writer Kinoko Nasu said that upcoming dungeon RPG sequel will have more voice acting and story volume than Fate/Extra PSP game, also that "eros" and "a girl’s passion" are themes for the story. It's also known that a mysterious girl who looks a lot like the mainline Fate series' Sakura Matou will be instrumental to the alter-universe offshoot's plot.
The first Sakura-alike is named BB, and she's voiced by familiar voice actress Noriko Shitaya. Residing in the Tsukimihara Academy’s infirmary, she created the game's Sakura Labyrinth, but her origin is a mystery - she claims to be an unusual, dangerous AI. She also doesn't mind being called Bebe or Baby.
Then there's the more belligerent fighter Melt Lilith - voiced by Saori Hayami (Heaven's Lost Property's Ikaros)
Finally, get Passionrip - voiced by Yui Ogura (tsuritama's Sakura, Pet Girl of Sakurasou's Yuuko Kanda, .hack/Quantum's Hermit), who is initially friendly to the player character, but attacks when commanded by her "Mother."