The Strongest Sage with the Weakest Crest

The highest-ranking demon, Zaridias, has finally revived. Even Matthias can't compete with the overwhelming magical power ... Alma and Rurii try to recover the magic sword made by Matthias, who lies in the treasure house of the royal capital, but the demons take the students of the school as hostages and the get stuck... Can Matthias overcome this unprecedented predicament!?