Hajime gets thrown into a fantasy world as the literal weakest person in his class, then spends the series becoming monstrously overpowered through pure ruthlessness instead of chosen-one magic. The gap between "useless classmate everyone forgets about" and "someone willing to do things the heroes won't" is the actual story, not the power scaling. Watch it if you want to see a protagonist stop asking permission and start taking what he needs to survive.
Hajime Nagumo gets pulled into a fantasy world alongside his entire class, where each student receives a powerful role suited to their talents. Everyone walks away with something incredible. Hajime gets Synergist, a support class nobody wants, and watches helplessly as his classmates become heroes while he's treated as dead weight. When a dungeon expedition goes catastrophically wrong, Hajime gets separated from the group and left for dead in the depths. Trapped alone with nothing but his supposedly useless ability, he discovers that Synergist isn't weak at all, just misunderstood. Through relentless experimentation and sheer survival instinct, Hajime learns to combine materials and craft his way into becoming something far more dangerous than any classmate could imagine. What starts as a story about being overlooked becomes a dark descent into power gained through isolation and brutality. Hajime claws his way up from the bottom with a cold pragmatism that sets him apart from the naive heroes above. As he grows stronger, the question becomes whether the person he's becoming is someone he wants to be.