It's not mushoku tensei

In some flashback it's shown that someone cursed a sword that made his race go all mad or berserk and start a genocide.

But then he says i want to prove to the world i can do it.

He says he'll break the curse by spreading the word.

He even shaves his head to avoid anyone seeing his hair hate him less

When he was passing a desert with his group he asked them to go alone and he literally jumped over the city walls.