Black ★ Gold Saw has an appearance which is quite similar to Black ★ Rock Shooter, except for parts of her flaming red eye, long black hair fading down to red, red pair of curved horns on her head and a large sword with a golden blade with a black saw-edge called King Saw.... ಠ_ಠ Well she's tottaly different from Black ★ Rock Shooter.
Kousaka is the cosplayer behind that Black Gold Saw Cosplay while Minato cosplaying as Black Rock Shooter, basically In Anime they are not enemies thats why they seem to look chummy in this Black Gold Saw Cosplay picture, but when BRS turned into Insane BRS, they began to fight.