The Strongest Sage with the Weakest Crest 12 (manga)

After a little bit of trouble, Matthias and his party became A-rank adventurers, granting them access to their desired destination. However, along the way, they encounter a city controlled by a group of “demions”—a demon subspecies that specializes in teamwork! The demions are using a factory to create a powerful bomb, so Matthias makes the obvious decision to slay every demion in sight!