I Surrendered My Sword for a New Life as a Mage: Volume 4

After Sylvia's brush with death serves as a wake-up call, Soma's party members come back to school with a renewed determination to improve themselves and avoid repeating their careless mistake. But why was there a trap where there shouldn't have been in the first place? As Soma investigates, he learns of the dark force secretly lurking within the dungeon-and that the academy officials don't have it nearly as under control as they thought they did.