Ninja Gaiden Σ 2 is the industry's worst-kept secret since Star Craft II, but it looks like Tecmo held back one or two choice tid-bits for their big GDC "secret game" announcement.
The big ticket item is that Sigma 2 will feature online co-op over PlayStation Network. Gamers can pick from Ryu, Ayane or Ninja Gaiden: Dragon Sword's Momiji and play through the story together (not against each other).
That's the second "new" thing: you can play as Momiji, which won't mean much to anyone who didn't play Dragon Sword on the DS other than a fresh set of tits to stare at.
As for Sigma's last leading lady, Rachel, Producer Yosuke Hayashi would only say: "Maybe you'll see her. She's a very important part of Team Ninja..."
Gee, I wonder which part — the front or the back?