This Synopsis was written by me.
In the quaint city of Paris, France, Mireille Bouquet works undercover as a professional hit-woman. But her life becomes even more dangerous when she decides to follow up on an e-mail sent to her from Kirika Yumura, an amnesiac Japanese girl who invites Mireille to go on a "pilgrimage into the past." The only thing Kirika remembers about herself is that she's called "Noir", and her past and Mireille's are somehow intertwined("noir" is French for "black.") And despite her gentle nature, Kirika's killing skills with a gun are even more deadly than Mireille's. The only clue she possesses is an old pocket watch which plays an enchanting melody that is somehow familiar to Mireille. Reluctantly, Mireille agrees to partner up with Kirika and they codename their new assassination team "Noir."
With the watch's melody and their own longing to unravel the secrets of their pasts driving them, Mireille and Kirika travel around the world, taking on assassination jobs, and slowly bits of the truth are revealed to them. After gaining knowledge of the Soldates, an ancient organization that has somehow been secretly controlling both their lives("soldates" is French for "soldiers"), they continue to plunge deeper into the darkness. More mysteries arise, such as Chloe, a girl who claims to be the real Noir, and her secretive mentor Altena, as well as the deception and murder that continue to follow Mireille and Kirika as they try to catch the elusive Soldats without being caught themselves. Never truly trusting each other, the unlikely pair do all they can to unlock the real meaning of their codename, which is more than just the alias of an assassination team, but the name of an ancient fate, of two maidens whose tainted hands govern death - Noir!