One-Punch Man episode 21 is called "The Ultimate Dilemma", and that title couldn't be any more appropriate. The episode sees Saitama finally end the threat of the Monster Association's attack on the Super Fights martial arts tournament, with an ease that awes (if not frightens) the beaten down fighters in the arena, like Suriyu.
After ending the threat of the Monster Association's attack on Super Fights, Saitama finally becomes aware that the evil organization has been launching attacks all over various cities. With the Hero Association having stretched itself thin, the S-Class heroes have all taken the streets to end the threat. While that's great for the heroes, and the citizens, it ultimately leaves poor Saitama with little to do and facing his greatest foe of all: boredom.
While walking the empty city streets in depression, Saitama runs into his new friend King, who wonders why the young hero is so down. At first King thinks Saitama is depressed about being bald, and encourages his friend not to give up hope of growing his hair back. Saitama angrily explains that it's not the baldness that's bothering him, but rather:
"I've become too strong. No matter who I fight, I don't feel anything. I gain nothing from it. Thre's nothing I can learn from anyone... Not having room to grow means that I can't enjoy the process of growing. No matter how many monsters I defeat, inside, I'm bored out of my mind. I never thought being a hero could be so lonesome."
King tries to offer Saitama the suggestion of widening his social circle, but that's not what Saitama has in mind. After a bit more lamenting, King finallly has enough, and gives Saitama a decisive breakdown of why he's not yet the Ultimate Hero:
"Saitama, seems to me you're mistaking getting strong for reaching your destination. I doubt the path of becoming a hero ends so easily... It's inherently wrong to see satisfaction from fighting. Battling with great courage and benefiting society insn't that what gives a hero's existence meaning? In that respect, you've got a long road to walk before you can become the strongest hero... In other words, the pursuit of the ideal remains. You must still have a great deal of unrealized potential. And in that case, to say that you've reached the limit of your growth starts to sound shallow and arrogant, doesn't it?
What does it take to be the 'ultimate hero'? An unflinching sense of justice? The courage to face any hardship? Until you've found the answer to that question, how can you say you have time to feel bored?"
That unlikely wisdom from King is enough to revitalize Saitama in a big way - for all of a second. Ulitmately, the thought having to reflect on being the ultimate hero is even more boring to Saitama than being bored from fighting. An invitation to play video games with King is the only thing that moves him even slightly.
One-Punch Man Season 2 is now streaming on Hulu, and on Crunchyroll outside of the United States. The season is directed by Chikara Sakurai (Naruto Shippudenepisode director), for new production studio J.C. Staff. Yoshikazu Iwanami serves as sound director, and Chikashi Kubota contributes new character designs.