Just as Suiryu finds himself in the depths of despair, Saitama suddenly appears to help him out. But despite all Saitama's strength, there's still something bugging the hero that he just can't seem to shake.
Saitama is a superhero who has trained so hard that his hair has fallen out, and who can overcome any enemy with one punch. However, because he is so strong, he has become bored and frustrated that he wins all of his battles too easily.
One-Punch Man - The Troubles of the Strongest Synopsis and Schedule