While on the road to their field trip, Class 2-C's bus is enveloped in light, and the Goddess, Vicius, summons the students and their teacher to another world. The Goddess hopes to raise them as Heroes to defeat the Great Demon Empire, and she welcomes the students after appraising their abilities with her crystal. However, Mimori Touka is appraised as an E-Class, the lowest rank... and he's branded a trash hero.
Here in Alion, whenever the vast evil 
known as the Great Demon Empire appears,
‫هنا في أليون،
Hier in Alion haben wir jedes Mal, wenn das Böse,
der Große Dämonenkaiser, erschien,
Aquí en Alion,
Aquí en Alion,
Ici, en Alion,
dès lors que le mal refait surface,
Qui ad Alion, ogni volta
che appare il Grande Male,
Aqui em Alion,
Наше королевство Алайон