* While yes, Saitama can NOW kill monsters with a single punch, perhaps his greatest moment of badassery so far is in the second chapter, during the flashback of his fight with a crab monster. This is when he was just an ordinary guy with no powers. Said monster is initially wiping the floor with Saitama, until Saitama loops his necktie around one of the monster's eyes, and rips it out.
* The "Sparring" two parter with Genos. Genos goes for a massive blast that Saitama appears to dodge, but Genos was expecting that and charges at him landing a rain of punches that tear apart the side of a mountain just as his previously fired blast hits. Only for him to discover that what he tackled wasn't Saitama but an [[SpeedEchoes after image]].
** How does the spar session end? [[spoiler: Adhering to the rules not to hold back, Saitama prepares to [[http://www.mangareader.net/onepunch-man/18/10 punch Genos]] but pulls back and hits him with a forehead flick at the end. The after effect of his attack still manages to destroy the mountain behind the two completely.]]
* For a manga that deconstructs shounen tropes, it still managed to play one straight: namely, Saitama telling a Class-B Hero to [[{{Determinator}} never give up on working hard to advance beyond their limits.]] [[spoiler: This is after Saitama kills a [[OurDemonsAreDifferent giant propeller fan]] with one punch that a previous S-class hero (ranked 2nd) didn't completely destroy after it wiped out the B-rank hero's similarly ranked comrades.]]
* Saitama gets ''another one'' when [[spoiler: after destroying the meteor, two B-class heroes try to ruin his reputation, then attempt to [[BullyingADragon execute him in public.]] While the result [[CurbStompBattle was obvious]], his speech on why he's a hero in the first place was just awesome.]]
* Licenseless Rider versus the Sea King, an unpowered C-class hero against an unstoppable monster, knowing he has no chance, [[spoiler:but doing it because there's no-one else. Though he doesn't win, he saves Genos' life and buys enough time for Saitama to arrive.]] He even wins Saitama's respect for putting up a good fight.
** This is, itself, a CallBack to one of Saitama's lines, one that Genos himself thought was so important that he had to write it down: [[HoldTheLine If The Heroes Run And Hide, Who Will Stand And Fight?]]
* Saitama's fight against the Sea King. [[OneHitKill While it does end like pretty much all of his fights thus far,]] it is such an epic and devastating punch that its scope is simply... breathtaking. Even the crowd that witnessed it was awestruck. This could easily be said to be the strongest punch he has given so far.
** What makes it truly impressive is not just the power, but the SPEED! It's so fast that we don't even see the moment of the impact, just the aftermath.
** Don't forget about the aftermath where he praised the other heroes for being there by [[spoiler: lying to the civilians that the other heroes had weakened the Sea King so he could finish it off.]]
* [[LittleMissBadass Tatsumaki]] ''stopping'' a whole bunch of [[BuffySpeak missile things]] thanks to her psychic powers, and ''sending them back to the Alien starship which fired them'' like it's nothing.
* How Saitama defeated [[AlienInvasion Boros]]: [[spoiler: He punched back his [[LimitBreak Planet Buster Roar Cannon]] that can destroy Earth's surface and not only did he utterly [[OneHitKill annihilate]] Boros, he also ended up destroying his massive ship and clearing a large part of the atmosphere from the clouds by ''[[http://www.mangareader.net/onepunch-man/48/32 creating a massive gap in the sky that was easily multiple kilometers in length and width]]'', reminiscent to how [[TheBible Moses parted the Red Sea]], all through the sheer shockwave effect that he released through that one punch.]]
** Not only that, but Boros' [[LastWords dying words]] [[spoiler: implied that Saitama ''was still holding back during their fight''. He ''split the sky'' with a punch, and that was ''still'' not his full power.]] [[StoryBreakerPower Way too strong indeed]]...
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