One-strike Knight

Caleb is the son of a farmer who dreams of one day becoming a knight who fights for justice and honor after he was rescued by a Knight in his childhood. For that purpose, he trained alone relentlessly in the art of swordsmanship but only managed to properly do one technique; a simple overhead strike.

Years later, after he had reached 17 years-old, he was allowed by his father to go to the kingdom's capital city of Justisia and enter the King's Sword Academy.
During his travels, he meets various people and encounters numerous foes and when the time came to take the entrance exam, he passes with flying colors much to his surprise.

Now why is that? That is because there was one thing that was certain when he displayed his swordsmanship;

His single technique can cut apart anything with a single swing.