Akuma has been unveiled as a character in Street Fighter IV -- but only as an opponent (far as we know). Players doing well in the single player mode will see the "strong demon" showing up to kick their arse.
Included is some artwork and in-game shots of ol' Gouki himself. Also, here's a video of him in action, straight out of Japan's arcades:
As of today, if you're playing Street Fighter IV in Japan in the single player mode, you may get to face off against a blast from the past: Akuma.
Leave it to Capcom to introduce a new character a month after the cabinets has been out in game centers. First introduced in Street Fighter II Turbo as a secret character as well, Akuma -- or Gouki, as he's known in Japan -- joins the lineup as a boss.
In order to get a chance at battling against the secret character, you need to be doing well in the single player mode before he'll suddenly appear and challenge you to a fight.
Promotional images for SFIV had teased the presence of the character earlier this year, but so far there had been no real confirmation of his inclusion in the game.