One-Punch Man (2015)

S1E1 The Strongest Man

Saitama is a man who became a hero just for the thrill of it. After rescuing a child from a life-threatening situation, he committed to becoming a hero and dedicated three years to intense training. Now, with the ability to take down any foe with a single blow, he’s found himself feeling empty. Despite his incredible strength, he senses that he has sacrificed something far more valuable along the way.