Tsuihou sarenakatta Otoko: Nidome no Jinsei wa Dogeza kara Hajimarimashita

A mere villager, Cross Vish, somehow ended up joining the hero's party by some strange twist of fate. Cross, an ordinary man with no special powers whatsoever. Yet, for some reason, the heroes genuinely considered Cross a true comrade. There was no way he would ever be banished from the party. And that was precisely why Cross kept agonizing. What could a useless person like him possibly contribute to the hero's party? And then... Cross came to understand his role. At the very moment when the Demon King, on the verge of death, unleashed magic toward the hero—

(Source: Kodansha, translated)