She is an Asian woman with brown eyes and dark brown hair.
Yuki seems to be an overly invested kind of officer, especially when it came to investigating Joey Quinn for corruption. This can be noticed when even after Debra Morgan refuses to become a rat in exchange for a shield she can't take no for an answer. She can also be very cold, trying to force Debra to give her information on Quinn by using past meetings to try and blackmail her. She also has a very high opinion of herself as demonstrated when she couldn't realize that it was her pushing Debra that made her confess to Joey rather trying to blame the whole thing on Debra.
Before she transferred to Internal Affairs she was partnered with Detective Joey Quinn in Narcotics. While she was working with Quinn she picked up a personal vendetta for him allowing a fellow officer in Narcotics named Detective Stewart to be consumed by an addiction which resulted in the officer in question shooting a man, paralyzing him from the waist down and then shooting himself in the head. After this incident she transfers to Internal Affairs with the specific intention to make sure Quinn doesn't use anymore shortcuts that end up costing a man's life and at some unknown point is promoted to Sergeant.
After Quinn transfers to Homicide she decides to use Officer Debra Morgan to snitch against Joey in exchange for a detective's badge. Even after Debra repeatedly told her no, she wouldn't take no for an answer. She began stalking Debra with constant phone calls, texts, and even showing up where she worked. She even went so far as to say that she would spread the word that Deb had been completely cooperative, which would have given her a reputation among other officers as a rat anyways. This, however, backfires as Debra tells Joey about her investigation and has it shut down. Yuki then stopped by one last time to make Debra feel bad about letting Joey know. Since then she has not been seen.