Louis Miller grows up in a poor, remote northern village, eking out a grim existence working in a brothel. His life changes when he discovers a textbook on elementary magecraft. Memorizing its contents in a single week, the rough and rowdy boy attracts the attention of a professor from Minervas Mage Training Institution, who is impressed by Louis raw talent and invites him to study at the prestigious academy on a scholarship.

Surrounded by nobles at the elite institution, the boy from the countryside is treated as a problem child. His aggressive, street-smart fighting style, which often incorporates dirty physical attacks alongside magic, makes him feared by fellow students who watch him mercilessly trounce opponents in magic battles. Despite his wicked streak and reputation as a violent thug, Louis finds teachers who respect his abilities and begins forming genuine friendships that will shape the man he is destined to become. The story follows his journey from an appalling little gremlin of a student into the composed yet nasty-tongued Barrier Mage known in the main series.

Central to his development is his budding relationship with Rosalie, a kind and somewhat stoic girl who will eventually become his wife. The two form an immediate connection, though their romance takes the entire volume to culminate in a confession. Louis also gains a mentor in Gideon, a teacher who recognizes that his student grows stronger through harsh beatings rather than praise. Throughout his six years at the academy, Louis sheds his heavy northern accent, a change he later makes to gain approval for his marriage to Rosalie.

This two-part prequel, complete in two volumes, reveals the notorious deeds of the Barrier Mages youth and explains how a destitute boy from a bordello rose to become one of the Seven Sages, the most powerful mages in the Kingdom of Ridill.