Katja 7z - Brandis,

The "7z" in your request likely refers to the in her overarching walker universe, which is the first book of the sequel series: Woodwalkers: The Return (Season 2), Volume 1: Das Vermächtnis der Wandler (The Legacy of the Shifters).

Clearwater High, a secret boarding school for shapeshifters. Brandis, Katja 7z

Carag, the cougar-shifter, returns as the lead character. The "7z" in your request likely refers to

Carag's Transformation (The Woodwalkers Book 1) - Amazon.com Brandis, Katja 7z