Akira Tanaka dies a quiet, unfulfilled death as a corporate wage slave, having spent his entire youth studying and working with no time for joy or romance. When he awakens as a newborn in a fantasy world of magic and swords, he is overjoyed. This is his second life, and he vows to live it differently. He will abandon the rigid path of a hero or a noble, pursue his simple hobbies, and become a humble, carefree artisan.

The story is set in the Kingdom of Eldoria, a realm where magical talent often dictates social status. Akira is reborn as the first son of a poor but kind-hearted blacksmith in a remote village. Using his past life’s disciplined intellect, he quickly masters the local craft, revolutionizing simple tools and trinkets. He grows up alongside Lilia, the cheerful daughter of the village innkeeper, and Roderick, a clumsy but earnest boy who dreams of knighthood. For a while, Akira's peaceful second life seems within reach.

The central conflict ignites when a royal inspection party arrives, led by the cold and politically astute Princess Serena. She discovers Akira’s innovative magical devices, items that function without incantations. The Kingdom’s rigid noble courts view his creations as heretical threats to the magical hierarchy. Accused of wielding forbidden "Null Magic," Akira is forcibly conscripted into the Royal Academy to be studied and controlled. His dream of a simple life is shattered.

As Akira navigates the hostile halls of the academy, the narrative unfolds through several arcs. The Academy Conscription Arc sees him clashing with traditionalist mages and reluctantly befriending the prickly Princess Serena, who begins to see his inventions as military assets. The Frontier Rebellion Arc follows when border lords attempt to kidnap Akira, forcing him to use his gadgets to protect his village, revealing he cannot remain neutral in the kingdom's politics. The Forbidden Past Arc uncovers that the "Null Magic" is actually an ancient, forgotten science from a lost civilization, and that the current magical system is a corrupted, controlled version of it. This revelation makes Akira the target of a secret order seeking to maintain the status quo.

Ultimately, the series follows Akira’s struggle between his desire for anonymity and his growing responsibility to the people he cares about. He must decide whether to remain the humble artisan he wanted to be or embrace the revolutionary role the world is forcing him to play, rewriting the very laws of magic and society.