El inútil de rango supremo

In a post-apocalyptic world, slum teen Ethan awakens SSS-rank fire phoenix power to save his infected sister, but is framed as E-rank waste by rival Mack. He secretly rescues others, finally kills four Level-12 beast emperors alone during a super horde, becomes humanity's hero, punishes villains, and moves to District 1 with his sister.