Kjersti Trollson first debuts in Frankie Stein and the New Ghoul at School in the Monster High Diaries.
Monster High Dairies
Kjersti meets Frankie when Frankie is looking for her little sister Zappit. She is a new exchange student at Monster High, and is paired with Batsy Claro and Venus and Ghoulia to look for Zappit. Frankie Stein and the New Ghoul at School