Tate no Yuusha no Nariagari

Tate no Yuusha no Nariagari takes the isekai formula and turns it into something much darker right away. Naofumi is called to be the Shield Hero, which is what he thought it would be—a typical power fantasy. But instead, he is falsely accused of a serious crime almost right away and publicly destroyed by the kingdom he is supposed to save. This horrible betrayal turns him from a hopeful newcomer into a deeply cynical survivalist who doesn't trust anyone. His famous shield can't attack at all, so he has to make a party out of people who don't fit in with society, starting with Raphtalia, a demi-human slave he buys out of desperation. It's interesting to see someone protect a world that hates him and fight his way back with practical thinking and smart business moves instead of friendship speeches or brute force. It's about rebuilding from rock bottom when the whole system is set up to fail you. This creates a satisfying underdog story based on justified anger and strategic thinking instead of the usual hero idealism.