In early episodes, Sarah is bubbly and slightly wild (at least in spirit), often pushing Saffron to go outside her comfort zone socially.
In later seasons, the abuse from Edina and Patsy has taken a physical and mental toll on Sarah. She is scarred on one side of her neck, as a result of Edina setting Sarah's hair on fire (which is not shown on screen). She is also quite unstable and has been in and out of therapy and mental institutions.
Sarah is played by Naoko Mori.