Eirei-tachi kara Shuugyou wo Uketsuzuketa Saigo no Eiyuu wa, Yagate Saikyou e to Nariagaru

To save his younger brother, the older brother chose to fight. In a world where dungeons suddenly appeared, monsters overflowed, and people fought using special skills, Uchida Mamoru was looked down upon as a useless person unable to use any skills. One day, framed by classmates and losing everything through false accusations, he is at a loss when he is suddenly dragged into a dungeon. There, his skill finally awakens. Source: MU