The Strongest Sage with the Weakest Crest 07

Once the world's most powerful sage, reborn Matthias has gained the optimal crest for magical combat many thousands of years in the future. But with magical knowledge at an all-time low in this new era, no one recognizes Matthias's crest for what it is, and it will be an uphill battle for the twelve-year-old sage to prove his greatness to everyone! The demons assault the Second Academy, which has gotten wise to their plot to cripple mankind through magic disinformation, with a veritable legion of summoned monsters to destroy everyone with knowledge of their scheme. But while the freshly trained up students of the Second Academy are faring well enough, things take a turn for the worse when the overwhelming Void Eater appears. How can Matthias possibly stand against a monster that towers over even the towers of the capital?!

Volume 7 of The Strongest Sage with the Weakest Crest manga series by Shinkoshoto.