Kori is like... The unofficial encyclopedia for all things Sakura Shinguji.
Anyway, I doubt this game will be released in Japan without additional characters. Cannot see SEGA Japan letting this title fly into retail spaces with flops like Sonic, AiAi, Beat and Vyse being the major characters. Game would probably struggle 50k across all platforms, if that, with it's current roster in Japan.
Neither can i even though SMB always seem to be the most popular title in Japan from the characters you listed, they alone wouldn't be enough to entice your average Japanese consumer. You're going to get the inevitable, "Where's this character?. Who the hell is this guy? Why is she in this game?!" To the japanese Sega fan they should be aright with some of the roster but not all of it and to the public they will say, "Sega superstars? There is NO superstar in this game." Alright, a bit of an exaggeration but you know what i'm getting at.