Cool Dimension: Innocent Assassin.

Kidnapped in childhood. Raised as an assassin. Shiori's spent her entire life following the orders of her mysterious masters, never questioning the commands that have sentenced hundreds to die at her hands. But when a childhood memory suddenly resurfaces, the programming in her head is short circuited and her entire world is turned upside down! Now, before her masters realize she's slipped their leash, Shiori has to escape. But to do so means she must kill again... even the ones who are close to her!