Darker than Black: Ryuusei no Gemini

Suou Pavlichenko lives an ordinary school life in Russia until her twin brother Shion becomes a Contractor and armed agents invade their home. During the attack she encounters Hei, the feared Black Reaper, and is pulled into the covert conflict surrounding Contractors.

Suou soon manifests an ability of her own and travels with Hei while questioning her memories, family, and humanity. In Tokyo, signs connected to the missing Doll Yin point toward a disaster, drawing their separate journeys toward the same mysterious prophecy.