Yep "we can't add additional characters over DLC". Nice try Bamco ~_~
Naruto Storm 3 DLC – Sage Kabuto Confirmed | Saiyan Island
YOSH! A brand new scan from Shonen Jump came out today showing what could possibly be a story mode expansion DLC (Downloadable Content) of Sage Kabuto vs Edo Itachi and Sasuke. Just to be clear, it’s not confirmed if there will be a story mode expansion, but Sage Kabuto will be making an appearance in some shape or form via DLC.
Naruto Shippuden: Ultimate Ninja Storm 3 is Namco Bandai Games and CyberConnect2′s fourth entry in the Storm series. It was released for the PlayStation 3 and Microsoft Xbox 360 in North America/South America on March 5 and Europe/Australia on March 8, and will be released in Japan on April 18, 2013. The story for the game will begin with the Nine Tailed Fox incident from 16 years ago, continue on to the Five Kage Arc, and go up to the Shinobi War, covering the latest episodes of Naruto Shippuden as they air in Japan.