As Saitama is waiting for the Hero Association to decide whether they want him to help fight the Deep Sea King or not, Genos initiates battle, and seemingly defeats the monster with a massive attack. However, he lets his guard down and gets one of his arms ripped off. He tells the townspeople to run while he distracts the monster, since victory is no longer assured. He seems to be doing a good job, until the Deep Sea King launches a glob of acid at a child, which Genos intercepts, and it melts his bionic body, nearly killing him. In that moment, right before the Sea King would have finished Genos off, Mumen Rider appears and engages the Deep Sea King. He is defeated easily, but refuses to give up. Upon seeing this, the townspeople decide to encourage him, but to no avail. When Mumen Rider is knocked out, he is caught by Saitama, who had been instructed by the Association to provide backup and arrives in that exact moment. After exchanging a few words with the Deep Sea King, he defeats him with a single punch which also stops the rain and is praised by the townspeople. Sonic also reappears with his weapons in a different part of town, but assumes the Sea King must have fled. Back at their apartment, Genos and Saitama get a delivery of fan mail from the Hero Association. Genos is praised, while Saitama gets a hateful letter, calling him a cheat. The episode reverts to a flashback from right after Saitama’s victory. The townspeople are ecstatic to have been saved and are impressed by Saitama’s swift victory. However, one of them starts badmouthing the other heroes, saying how they must have been frauds, no matter their rank, since they got beaten. His reasoning is that the Deep Sea King could not have been that tough if a Class C hero defeated it in one punch. Upon hearing this, Saitama laughs, and downplays his victory to save the reputations of the other heroes by saying that he got lucky and the job was easy for him, since he came late and the monster had been weakened. He also tells the townspeople to care for the fallen heroes, so he can continue to cash in on their work. The townspeople accept him as nothing but a fraud and thank the defeated heroes for their work. Genos decides not to interfere with Saitama’s decision, but promises to intervene if this choice were ever to push Saitama into a corner in the future. The episode jumps back to present time, and Saitama realizes he has another letter – this one only saying “Thank You!”. He then finds a third letter from the Hero Association, telling him he is now 1st Rank C-class, and calling him in to discuss a promotion to B class. Saitama accepts, making him 101st Rank, B-class. The episode jumps to Amai Mask during what seems to be a photo shoot. One of his subordinates tells him that Saitama moved up a rank. Amai Mask seems to not care, as he is disappointed by the work of the A- and S-Rank heroes in the Sea King case. However, he changes his mind when he is told that Saitama was the one to actually defeat the monster. Meanwhile in the hospital, Lightning Mask and Stinger are recuperating when Puri-Puri Prisoner enters wanting to administer “Angel Shots” to the two. They escape, dropping the newspapers they had been reading, and Puri-Puri Prisoner is upset when he sees that he is called an “S-Rank Failure” in the news. The episode ends with Saitama walking home at night with his promotion. He encounters Mumen Rider in a roadside oden shop. Mumen Rider reveals he sent the thank-you letter and pays for Saitama’s dinner. In the post-credits, a fortune teller named Madame Shibabawa warns an official from the Hero Association that “the Earth is doomed”.
The episode opens with an octopus-like monster announcing that the Seafolk are coming to the surface to kill all the humans. Saitama is on his way home from shopping and stops by to punch the messenger. Mumen Rider is late to the scene and sees only the destroyed body of the creature, and hears the crowd talking about Saitama. Mumen looks Saitama up on the internet and sees that he is powerful, but opinions are divided on him. At the coast, several large Sea-Folk monsters emerge from the sea, threatening City J. The Class A hero Stinger (rank 11) challenges them with his powerful Bamboo Shoot weapon. Meanwhile, Genos is drying dishes with his rocket hands as Saitama watches a news report about Stinger’s battle against the Sea-Folk. They decide to head out to confront the threat. Back at the fight, Stinger takes out the last four Seafolk with a Gigantic Drill Stinger Quadruple Thrust attack, but is then bested by a new monster: Deep Sea King. Saitama, Genos, and Mumen Rider all set off to confront the threat. Genos splits off from Saitama to scout ahead. Various other heroes confront Deep Sea King to no avail, including Lightning Max (class A), Puri-Puri Prisoner (class S), and Sonic (not technically a hero). Sonic fights Sea King to a standstill, but when it starts raining, Sea King unleashes his true form and Sonic is forced to retreat. Meanwhile, Saitama and Mumen Rider meet each other on the way to the fight. Saitama goes off to find Sonic who he sees running naked through the rain. Mumen gets a phone call from Hero Association headquarters and goes to confront Sea King, who has broken into an emergency shelter and is dispatching the heroes there ranging from All Back-Man, Bunbunman, Jet Nice Guy, and Sneck. Saitama returns to where he met Mumen Rider to find a discarded cell phone. The episode ends with Saitama telling the Hero Association he is on his way.
Just before an incident, scientists and astronomers are busy studying the flight pattern of a meteorite just as it passes over the earth. When its course suddenly changes trajectory a mass warning system breaks out that a huge meteor is about to strike City Z. A notice is sent out to all S-Class heroes to intercept the meteor. Genos receives the notice while at home, conversing with Saitama about hero rankings. However, only Genos arrives on the scene, followed by an aged S-Class hero Bang. He tells Genos the meteor evacuation protocols have already began and that he should clear out before it is too late, Bang himself cannot leave the city due to family honor and personal reasons, and before he could formally introduce himself, Genos has already left. Genos theorizes that it is too late to evacuate, seeing the meteor approaching too fast. His resolutions affirmed when he realized that his master also lives in this city. Another S-Class hero named Metal Knight shows up to test out a new weapon against the meteor but is uninterested in teaming up with another hero to avert the crisis. When his new weapon fails, Genos used his own prototype weapon on the meteor. Despite the overwhelming power displayed, he fails to stop the meteor. Saitama shows up and destroys the meteor with a single punch, impressing Bang and boosting Genos’ admiration toward Saitama. However, the meteor shatters into several meteorites and still manages to destroy the city. The next day, Saitama learns that his rank has jumped from 300th to 5th, although he still remains a C-Class hero. Genos theorizes that, despite Saitama’s S-Class achievement, people must have believed it was Genos and Metal Knight who had destroyed the meteor. After a quick discussion about threat levels and words of being a hero that inspires Genos, Saitama goes out to look for more crisis to boost his own rank. Much of the city is destroyed but despite that, there are zero casualties reported. Tanktop Tiger appears and believes Saitama has stolen credit for the meteor destruction. Tanktop Tiger calls his brother Tanktop Black Hole, who begins to rally up a mob against Saitama, putting all the blame on him for the city’s destruction. Tanktop Tiger attacks Saitama, who was later punched into the sky. Tanktop Blackhole attacks next, and Saitama catches his fist, crushing it. Saitama then moves on to the crowd, who were chanting for his resignation, and he shouts for everyone to shut up. Saitama clarifies that he is being a hero because he wants to and does not need to be appreciated for it. Genos appears and tells Saitama that it is time for them to go home, and speaking internally, despite what the world thinks of Saitama, he knows that his master is the greatest hero of all. In the post-credits, a myriad of creatures located under the sea discuss Saitama’s victory over the meteor.
Saitama is shown lazing about and reading manga as Genos studies his unorthodox training methods, recording his every move. Saitama contemplates how much of a pain it will be to keep up the charade of being Genos’ master when the cyborg mentions his concern over his inactivity over the past few days; due to an overabundance of C-Class heroes, the Association eventually strike those who are inactive for more than a week from their registry. Shocked and horrified by this revelation, Saitama sets out on patrol. Genos wishes to accompany him but Saitama rebuffs his request, telling his pupil to train himself in patience. In reality, Saitama does not know how or in what way to instruct Genos. Having been out on patrol for two utterly uneventful days, Saitama becomes nervous, as this is his last day to avoid losing his official status. To make matters worse, Speed-o’-Sound Sonic shows up to settle their (imaginary) rivalry, only for Saitama to brush him off. Angered, Sonic attacks, only to have Saitama bite his sword in half. Greatly bewildered by these events, Sonic finds himself intimidated by the irked Saitama, who threatens to hit him just as a bystander sitting next to a boisterous upper-ranked hero revealing to be Tanktop Tiger, who reproaches Saitama’s crazed antics; when the Tanktop Tiger began reveling in public adoration he later enticed Saitama to make a big deal out of it just to entice his own rise in popularity only to be cut down by a hail of exploding shuriken which sends the crowding masses into a panic. Recognizing Sonic to be the culprit, the assailant soon forces his hand by causing havoc around the populated area with a lethal bombardment. While still busy looking for hero work to do, Saitama realizes Sonic had provided him with the pick-me-up he needed and swiftly knocks the latter out cold, saving the day. Later that day around Saitama’s old neighborhood, a mysterious being was seen skulking around frightening the few masses who lived in the desolate Z-City; perturbed at not being sent out to deal with it, Tatsumaki berates the assignment staff. They have already sent out A-Class’ Golden Ball and Spring Mustachio out to the scene. In Z-City the two aforementioned heroes are busy patrolling the streets, wondering about a rumor of a pretty dangerous monster who lives in said area. After finding next to nothing on the job, they eventually find signs of said Mysterious Being and chase after it. Running into Kombu Infinity, who also heard rumors of a powerful group of monsters in the city, engaged the duo and easily swats the best efforts of both aside. Realizing they are outmatched, Mustachio dials for reinforcements just before he is swiftly defeated. Upset that his opponents were so weak, Kombu sets out to create the rumor he and his fellow monsters initially heard about; soon after Saitama returns from a market sale, when Kombu notices him as the former relents on not having been able to secure some kombu soup stalk just before the monster attacks him. When next seen, Saitama is just cooking some kombu soup when Genos comes in. In the post-credits, Genos tells Saitama that, while he’s in 17th place within the S-class, he’s ranked 7th in popularity, much to Saitama’s dismay. Genos then starts reading some online comments about him, but a jealous Saitama tells him to stop.
Inside the cathedral, a group of nuns are crushed to their deaths, leaving the surviving priest awestruck. Eren and Annie fight each other in their Titan forms throughout the Stohess District, causing destruction and civilian deaths while Hange orders her men to stand by before they capture Annie. Meanwhile, Erwin tells Nile that he will accept responsibility for the damage his plan has caused, for which Nile has Erwin arrested and orders the Military Police to help evacuate the civilians. After exchanging several blows, a berserk Eren completely overpowers Annie, who attempts to escape by climbing up Wall Sina. However, Mikasa cuts off Annie’s fingers, sending her falling. As Annie falls, she remembers her father asking for forgiveness, telling her to hate the world and asking her to promise him she will come back home. When it appears Eren is about to eat Annie, he stops once he sees her crying, and her body starts encasing itself in crystal. As Eren recuperates, he admits to Mikasa, Armin and Jean that he allowed Annie to get herself encased. As Armin and Jean wonder if sacrificing their humanity to defeat the Titans is worth the price, Erwin attends a government inquiry, where he reveals that he kept his plans secret to prevent leaks. He further explains that despite the deaths and casualties of his plan and how they cannot get any information from Annie now that she is encased, she is proof there are humans that can turn into Titans living within the walls and he plans to find and use them to launch a counterattack against the Titans. In the end, Erwin’s name is cleared, Eren stays with the Scout Regiment, Annie is put under the Scout Regiment’s custody and the rest of the 104th Top Trainees go on their different missions. In the epilogue, a piece of Wall Sina crumbles, revealing the face of a Titan within the wall.
A few days before Eren is escorted to the capital, Erwin and Armin reveal to him they have a plan to capture the person they believe is the Female Titan and is shocked when they tell him it is Annie. Back in the present, Eren, Mikasa and Armin manage to escape a tunnel collapse while being hunted by Annie in Titan form. Eren tries to transform but is unable to, and Mikasa suspects that his feelings for Annie are preventing him to do so. When Eren is trapped in another tunnel collapse, Mikasa and Armin distract Annie away from Eren. Meanwhile, Commander Nile Dawk of the Military Police demands an explanation from Erwin on what is happening as his men hold him at gunpoint. Mikasa and the rest of the Scout Regiment distract and try to capture Annie, while Armin and Jean attempt to free Eren from the rubble. Armin tells Eren that he has to fight Annie as anyone who refuses to sacrifice can never change anything. As Eren thinks about what Armin said, he remembers his hatred for the Smiling Titan who killed his mother. Eren finally transforms into the Rogue Titan and charges at Annie in a rage, smashing into a cathedral.
Annie has a dream of being trained by her father before waking up. In the Stohess District of Wall Sina, the Military Police are ordered to escort the Scout Regiment convoy once they enter the capital. The Military Police are shown to be lazy and corrupt which one of Annie’s colleagues named Hitch Dreyse reveals she joined the police for that reason. Another colleague named Marlo Sand is disgusted, revealing he joined the Military Police so he could reform it to become a better organization, which Annie respects since he reminds her of Eren. After the convoy has entered the Stohess District, Annie is secretly called by Armin in the alleyways. Armin asks for her help, as he is helping Eren escape the capital, and the one riding in the convoy is actually Jean in disguise. Although refusing at first, she finally agrees after Armin begs again, believing she is a good person. Armin leads Eren, Mikasa and Annie to an underground tunnel. However, Annie refuses to enter as she has noticed Armin behaving strangely and hidden Scouts watching her. Armin finally reveals his suspicion that Annie is the Female Titan, noting that she used Marco’s Omni-directional Mobility Gear to kill Sawney and Beane and that Female Titan did not kill him during the last expedition. Eren and Armin beg Annie to prove them wrong by following them, but knowing her identity is exposed, Annie laughs sadly and tries to transform. Despite the Scouts’ attempts to bind and gag her, she succeeds in transforming using the spike in her ring.
Levi, who orders Mikasa to distract the Female Titan in order to get Eren back, successfully debilitates the Female Titan at high speeds, but he injures his leg in the process when saving Mikasa from the Female Titan after leaving herself vulnerable when attempting to finish off. Mikasa then goes with Levi, who retrieves Eren from inside the mouth of the Female Titan, leaving it badly wounded and slumped against a tree. The Scout Regiment mournfully retrieve the corpses of their fallen comrades, with Erwin ordering that the lost corpses be reported missing in action. However, a Scout named Dieter retrieves the corpse of his friend Ivan against this direct order, which draws the attention of two Titans to the retreating Scout Regiment. Mikasa kills one of the Titans to save Dieter, who loses both Ivan’s corpse and his friend Jurgen. In order to outrun the remaining Titan, Levi reluctantly orders some of the corpses, including Petra’s, be disposed of in order to lighten the wagon’s load. Later, Eren wakes up from a dream of his past to find himself and the Scout Regiment back at town, safely behind Wall Sina. He becomes angry upon hearing the townspeople berate the Scout Regiment’s ineptitude, until he sees a boy who admires their bravery, which sends him into tears. All the while, a shocked Levi is questioned by Petra’s father over his daughter’s whereabouts, who reveals that Petra planned on devoting her life to Levi. The townspeople also become enraged and upset at Erwin over the failure of the mission and the casualties that were sustained. As a result of the failed expedition, Erwin and his subordinates are summoned to the capital, where the final decision of Eren’s custody will be made.
Erwin tells Hange that it was a mistake to think all humans who can transform into Titans are like Eren since the Female Titan has unique abilities far beyond that of a novice, while elsewhere the mole transforms into the Female Titan and chases after Levi’s squad. Armin theorizes the mole is someone who had seen Eren transform during the invasion of the Trost District. Eren wants to transform into his Titan form, but the squad tells him to trust in their skills and keep moving forward. Petra, Ouro and Eld manage to blind the Female Titan and attempt to cut off her arms and kill her. However, the Female Titan manages to quickly regenerate her right eye and kills the three. Seeing his comrades dead, a grieving Eren transforms into his Titan form, which gets Mikasa and Levi’s attention. Believing his comrades and squad’s death could have been avoided if he had transformed in the first place, Eren fights the Female Titan in a long battle. The Female Titan finally defeats Eren by taking off his head and swallowing his human body. Mikasa attempts to stop the Female Titan, but to no avail. She is later joined by Levi, who tells her to keep their distance, as the Female Titan is getting tired.