Youheidan no Itoshigo: Shinikake Koji wa Saikyou Shishou-tachi ni Sodaterareru

Young Will was an orphan with no one to rely on. He was dying in a corner of the slums when he was saved by a mercenary who happened to pass by. Will wanted to join the mercenary group in order to survive. He was given an impossible entrance test—but his talent was recognized, and he was provisionally accepted into the kingdom's strongest mercenary group!? Under the guidance of the group's members, who are among the world's greatest fighters, Will's extraordinary potential blossoms, and before he knew it, he was respected by the members as well—!? The ultimate growth fantasy of an extraordinary disciple raised by invincible masters!

(Source: Kadokawa, translated)