Ep 12. The Strongest Hero

Saitama has been waiting for a challenging opponent for quite some time but as he took down all his enemies with one punch, he got no excitement in that. However, he finally meets the one of the strongest beings in the universe, Boros, and he seems to provide the thrill that Saitama has been looking for.

Boros, the leader of the Dark Matter Thieves, invades the Earth and his first target is City A. Saitama heads there with the help of Bang, King and Genos, while the remaining S-class heroes fight other members of the Dark Matter Thieves in different cities. They faced a lot of troubles on their way like due to the energy blast caused by the enemy's spaceship, they crash-landed into the ship. After fighting various levels of the spaceship guards, Saitama and Boros finally face each other.

The encounter between the two is nothing short of explosive, with both fighters showcasing their immense power. Boros is the first one to attack and uses his overwhelming strength to form massive energy waves. But Saitama is unfazed and easily dodges the attack. Boros then powers up and unleashes his ultimate attack, the "Collapsing Star Roaring Cannon." At first, it seems like Saitama is on the receiving end of the attack, but he stands his ground and delivers a counterattack, which ends up destroying the ship.

After the battle with Boros, Saitama's powers and overwhelming strength are finally exposed to the public, and he becomes a hero that everyone is looking up to, being referred to as the "Strongest Hero". Saitama, however, is not happy with the title as he has not yet found someone who can give him a good fight and the excitement he has been longing for. Meanwhile, other S-class heroes are also shown facing their own battles against Dark Matter Thieves and still managed to come victorious in their fights, but what lies ahead is an even bigger threat that they must face together.

Overall, One-Punch Man Season 1 Episode 12, "The Strongest Hero," is an epic conclusion to an already thrilling season. The fight between Saitama and Boros is one of the most exciting scenes of the season, and it does not disappoint. The episode also gives viewers an insight into the other S-class heroes and their fights against the Dark Matter Thieves, creating a sense of unity in the show's superhero universe. The ending of the episode leaves viewers wanting more and sets up a promising Season 2.