yin

A member of Hei's team and an emotionless spirit medium known as a "doll." Her power lies in tracking and observation through water, effective only when she is in direct contact with it. Huang mentions her "program" is minimal, unable to show emotion or make independent decisions. However, she later proves this wrong by choosing to stay and work with Hei and the others when given the option to leave. Yin has Finnish origins, her real name being Kirsi, a diminutive form of Kirsikka (meaning "cherry") or Christina. She was once a student of the renowned Finnish pianist Eelis Kastinen (or Kostinen). Her father died in a plane crash, and shortly after, her mother was also tragically killed. Yin blames herself for her mother's death, believing that if she hadn't panicked and run away following a certain event, her mother wouldn't have jumped into traffic to save her. From what we see of her past, Yin appears to have poor eyesight or may be nearly blind, as she couldn't recognize when the moon was full or if her teacher found his dropped pen in episode 13/14. Yet, there are instances where Yin seems to perceive more than expected. Little is known about her transformation into a "doll," but it seems linked to her personal tragedy. It is implied she has feelings for Hei, as Amber noted their similarities and asked Yin to take care of him. Throughout the series, Yin begins to display emotions and her own will, deciding to follow Hei and remain his partner. She even observes changes in his behavior without being ordered to do so. This became evident when she called Hei from the void to return to her, not wanting to be left alone. In the process, her observation apparition evolved, now having a human-like body shaped like her silhouette and capable of physical touch. Episode two of Gaiden reveals that "Izanami" possessed Yin during episode twenty-five, explaining how she attained these abilities.