Decapre is one of M. Bison's Dolls; young women brainwashed and programmed into becoming his personal assassins and bodyguards. She is of Russian origin, and her name is derived from the Russian word for December.
She resembles Cammy almost identically, with a similar hairstyle, though her uniform is darker and she wears a face-concealing, Vega-like mask and wields claws like him his as well. In the Udon comics, the mask is to cover severe scarring on her face. In the comic, her resemblance to Cammy is also explained, as her being a prototype cloned body before Cammy was perfected. Neither of these elements have shown up in the games, however.
Decapre makes her first appearance as a playable character in Ultra Street Fighter IV. Her design in the game is very similar to her original appearance, though her mask has been modified to reveal her mouth. She also seems to carry katar instead of claws, as well.