Yuusha Densetsu no Uragawa de Ore wa Eiyuu Densetsu o Tsukurimasu: Oudou-goroshi no Eiyuutan

The winner of the 7th Net Novel Award! Yukina is an ordinary young man born in the same village as the hero destined to save the world. By chance, he comes into possession of the talking spear Gram. It is a weapon with abilities comparable to those of the hero's holy sword.

(Source: Futabanet, translated)