I Shall Create the Hero's Legend Behind the Hero's Legend: The Heroics of A Royal Road Killer summary:
Yukina was a young man who hailed from the same village as the Yuusha who shouldered the fate of the world. Through a certain incident, he got ahold of the talking spear, Gram. It was a weapon that was on par with the legendary sword the Hero wielded. The first volume of an adventure fantasy of the youth with a realistic growth!