Sorry, I haven't played Perfect yet, but assumed it'd have story-specific voice clips, like V did. If not, I can't really see why the new content would require the removal of old content, indeed.
Well, this "story mode" is just Kuroko trying to invite your char to a Tournament or Carnival, hosted by Yoshitora Tokugawa.
So, for ALL chars there are, 3 curtains which is the so called Story. First 2 are exactly the same for all.
On the first one, you see your character quiting place aftermatch. Kuroko is following and tells what a good warrior he have just seen.
On the second one, once your char leaves the place, Kuroko tries to reach fighter, but finaly asks deliver to give the invitation personally, then tells that you need to kill bosses with Issen (fatal flash) or Fatality (don't remember how this is called).
The third one is just an image of your char's face (similar artwork used to show dead Bosses), a text appears over it and fighter reads the invitation and just decides what to do (still, all text). Depending of the case, there are more lines explaining details.
[END]
That's all your (generic) story mode, Sir.
As you can see, this was more hype than anything else.