One-Punch Man (2015)

Saitama, a hero who initially sought excitement in heroics, has undergone three years of intense training, resulting in overwhelming strength that renders him nearly unbeatable. However, this immense power comes with an unexpected downside: defeating foes with a single punch has stripped away the thrill of battle. As he grapples with ennui and the monotony of his invincibility, Saitama continues to confront new adversaries daily. With his enthusiasm waning alongside his hair, the question looms—how much longer can he maintain his heroics in a world that no longer challenges him?