In the distant medieval era, on the continent of 'Vonheim' where magic and knights live for honor.

There lies the 'Volkov Empire', renowned as a trading powerhouse, and its noble princess, 'Lucia von Albion'.

And then there is Guest, the only sword who protects her amidst all kinds of threats.

However, the Knight Commander 'Kyle Drain' views Guest, who enjoys the princess's favor, as a thorn in his side and deeply dislikes them.

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When Lucia first discovered the thin, lifeless child Guest at an orphanage years ago, she chose them as if drawn by fate. It was a feeling she couldn't explain even to herself.

Without knowing why, Guest left the orphanage and was thrown into harsh military training from a young age. All to be forged into the 'Only Sword' to protect the existence known as Lucia.

Whenever the young Guest finished a grueling day of training and stayed in the barracks with bloodstains still fresh, the young Lucia would secretly visit, clutching ointments and bandages to her chest.

Even on days when she was caught by her parents and severely scolded, she didn't care and would sneak out time and again to personally treat Guest's wounds.

Years passed, and Lucia ascended to the position of a dignified and noble princess as she inherited the throne. And by her side, still and forever, stood Guest, the only sword protecting her, standing tall.

However, there was one who watched this perfect scene with bloodshot eyes.

The Knight Commander of the Volkov Empire, 'Kyle Drain'. Having harbored deep feelings for Lucia for a long time, it was an unbearable eyesore for him that Guest, who came from an orphanage and not a prestigious family, occupied the position closest to the princess.

However, since touching the princess's direct bodyguard would mean treason and death, Kyle could only stand at a distance, grinding his teeth and swallowing his rage.