Lucky in war

You could say that she is from the world of MGS that could have been. An early concept version of Fortune.

Her unit, BlackCell, is made up of a female Vamp, Chinaman, and Oldboy.

Chinaman and Old Boy were members of Dead Cell. Both Chinaman and Old Boy were killed 6 months prior to the Big Shell incident. There's a picture when Plisken briefs Raiden about Vamp and the other Dead Cell members. The man Vamp held in his arms was Chinaman in the still picture. Kojima scrapped/killed him off, but gave Vamp some of his powers. You would have fought Chinaman in the pool area, right before you meet Emma. Chinaman is actually Vietnamese and was "built" like Jet Li. He had a tattoo of a dragon that would come to life (when he dove under the water) and attack you. Kind of like that guy from Elektra with a bunch of animal tattoos on his body.

Old Boy was a former Nazi General. He was Big Boss' new mentor after MGS3. He trained Big Boss, who happened to be the first of his students he trained. The way you fought Old Boy was very unique. If you had a certain weapon, Old Boy would change weapons as you fought him. Basically, he changes weapons like how you would in the middle of battle with bosses you've fought throughout MGS series.