In that city, a peculiar urban legend circulated. “If one found themselves alone in a room at midnight, a ghost would slip through the window and stealthily enter. Once marked by its blade, there would be no escape, and life would quickly meet its end.” Only she and her master know that this urban legend hold some truth. Egret, a girl who was taken in by the assassination guild at a tender age, before she could even comprehend the world around her. She was raised as an instrument of assassination and utilized accordingly. Due to her exceptional aptitude for assassination, she was highly valued, but it also subjected her to rigorous training. Emotionally detached and carefully honed, she grew up to be an elite assassination tool, earning the moniker “Ghost.” On that day, her routine was the same as always—to carry out her assigned tasks. However, the job she received was different from the usual. It involved a target with a hidden secret. The mark was the eldest son of a duke—a man possessing military power on par with that of a “hero” within the immensely influential duke family. As she embarks on the mission to target an opponent of overwhelming strength, unexpected encounters and unforeseen events await her. Mana Doll. A humanoid weapon crafted in the ancient era of the magical civilization. Designed to resemble humans, capable of speech and thought, this tool took the form of a girl. The encounter with such a mana doll would transport her beyond the confines of her “ordinary” existence. Through a series of varied incidents and encounters, their bond would deepen. This is the story of a girl raised as a mere instrument who crosses paths with a girl created as a mana doll, ultimately embarking on her journey as a human.