Read manga: My Twin Sister Was Taken As A Miko And I Was Thrown Away But I'm Probably The Miko.

manga
Summary:

Relunda has always been treated unfairly, constantly compared to her twin sister, whose personality is bright and beautiful. One day Relunda was thrown away into the forest, abandoned by her parents when her sister was taken over to the Great Temple as a child...
In disappointment, the strongest monster Griffon in the forest and a Sky Horse helped her lonely person...