When she was younger, Kazuho tried to leap across a river but the ground was wet from rain, so she slipped and fell into the river. On his way to take his hero-course entrance exam, Koichi pulled her out of the water and gave her his silver age All Might hoodie.
Several years later, Kazuho reencounter Koichi while performing his street performances as Pop☆Step. Koichi notes that Pop☆Step is taking a big risk in being a freelance idol since she does not have a permit. A police vehicle is passing by, so Koichi warns Pop☆Step, who decides to end her live performance and flies away.
Later that night, while Koichi was returning home after an incident at work, he meets Kazuho again in an alley. She thanks him for helping her that morning but she make fun of him for being weak and wearing an All Might hoodie, which causes both to start arguing. Pop☆Step begins to leave but bumps into Soga and his friends. The thugs recognize her as the online idol, begin mocking her and even thinking to sexually assault her.
Scared, at first Koichi thinks about leaving her to her fate, but seeing her scared face decides to help her without thinking. He does not have much success at first, and all he gets is to anger even more Soga, but with the sudden appearance of Knuckleduster, between both defeat the thugs and save Kazuho.
After this meeting with Knuckleduster, Koichi becomes his pupil, and the three form the group that would become known not much later as the "Naruhata Vigilantes". Knuckleduster explains to both of them the personal mission in which he is involved: he is trying to dismantle the illegal traffic of a drug known as Trigger, which boost an individual's Quirk, simultaneously weakening their sense of reason.
Although Kazuho does not usually fight directly against the villains, he helps Koichi and Knuckledusters in their patrols, investigating for them, helping to evacuate the passers-by, providing first aid, etc... While continuing performing as street Idol. This makes him get involved in several problems, but also allows him to meet many other people who help him to ascend in the world of entertainment.
One of these people is Makoto Tsukauchi, a senior college student from the same university as Koichi.
Marukane music concert
When Kazuho Haneyama received an email request from her blog that asks her to join a live event on the roof of the Marukane Department Store, she fears that since people view her as a singing street performer and if she screws up they would desert her, yet this is a chance that does not appear often. To help her, Koichi brings Makoto to help with the situation at hand. Kazuho gets mad at Koichi for her knowing her secret identity, to which he replied Makoto has sharp intuition. Makoto promises to Kazuho that she would not mention her masked escapade to anyone.
Kazuho ends up being part of Feather Hats, a musical group composed by her; Feathers, an underground idol duo conformerd by the twins Miu and Yu, the band Mad Hatters and the East Naruhata High Dance Squad; and thanks to Makoto's business skills and contacts, She gets sponsors for Narufest.
The night of the premiere, in the greenroom, Kazuho Haneyama begins to feel nervous about going out on stage. However, a villain causes a blackout and everyone is worry that the show is called off, and Pop☆Step notices that Koichi Haimawari has gone off somewhere. Koichi emerges from the crowd as The Crawler. He gives Pop her microphone. Pop agrees with the plan for her to go on stage and keep the audience calm.
Pop☆Step explains to the crowd why the power went out, and that the staff are working hard to restore it. She then introduces herself to the audience. Pop instructs those with glow-sticks and assorted light-up goods to line up at the edge of the crowd, and for the rest of the audience to move a bit towards the stage to make a path. She tells the gathering of people that they have time to go to the bathroom before the main event, and that in the mean time she will perform a few songs. Miu & Yu note that she did some slick work on the stage. They also mention that she was as lame as ever, but kind of cute.
When the power is restored. Pop☆Step tells the crowd that the show will begin. The Feather Hats perform their remix of the Marukane Department Store Jingle, and they are greeted with great applause and cheering from the crowd, thats goes wild after the Feather Hats finish their performance.
Thanks to the show, Kazuho's popularity as Pop Step grows a lot, still she continues working as a Vigilante. During the days after the festival, Knuckleduster is increasingly absent, until finally he leaves without saying anything to anyone, leaving his mask and brass knuckles at Koichi's penthouse. Kazuho wonders why Knuckleduster would leave them there since they just parted in town.
Days later, Kazuho is chosen to represent Marukane Department Store in a regional idol collaboration show in Osaka, celebrated on SS Mall in Super Minami. Along the way they meet Fat Gum, who tells them in the address. Later, on the green room for the Mascot Idol Carnival inside the mall, Kazuho is recognized as Pop Step by Monika Kaniyashiki, an idol whose who works for the Kanidoge chain.
After interpreting the theme of Marukane Department Store in the Idol Show, Kazuho and Koichi decide to see the exhibitors and the souvenir shops of the venue. As they walk, they find Monika riding a crab-shaped Mech. That the Kanidoge's uses as walking advertisement. Monika has to leave for some business, and as it takes too long to return, her manager asks Kazuho to handle the mecha.
What they did not know is that Monika is a covert police investigating the illegal traffic of trigger, that used the products of Kanidoge to distribute the drug throughout Japan. Investigating Monika and the police find the main suspect, who activates a code that makes the Kanidoge’s mechas go on a rampage, and takes advantage to destroy all the evidences and escape.
When this happens, Kazuho is now trapped in a rampage mech, unable to free herself or stop the machine. Koichi tries to help her but fails. Fat Gum and Kaniko arrive and chase the mech to stop it. Monika asks Fat Gum to throw her to the mecha, allowing her to use his Super Move Rocket Crab Clip, and the mecha’s legs, preventing it from moving forward.
Monika quickly rescues Kazuho, just when the mecha starts its sequence of self-destruction. Monika, Koichi and Kazuho run as far as possible from the machine before it blows up, warning everyone present to leave. But Kazuho stumbles and Koichi launches to protect her, still too close to the mech. At this moment, Fat Gum appears and jumps to block the explosion of the Mecha, absorbing all the kinetic energy with his Fat Absorption Quirk, saving Koichi and Kazuho's life. He holds enough time for everyone to move away before releasing all the energy, at the cost of his protective fat.
To avoid problems, before they can be questioned by the police, Kazuho and Koichi leave the convention, and sleep on the train on the return trip.
Back to the routine
After the incident at the idol show, Kazuho returns with his daily life to continue with his studies, act in the Narufest of Marukane, and help Koichi from time to time when he decides to perform his activities as a vigilante. During one of his patrols, Koichi discovers a new power of his Quirk, the ability to shoot repulsion force blasts, wich he names it as Scrappy Thrust Style. He later shows to Kazuho this new power, explaining her the process to execute it and starts throwing blasts until he accidentally breaks a windowpane. 
The next day, despite her scold, she surprises Koichi training the Scrappy Thrust Style. She scold him again, and advises him to not shoot repulsion blasts because he could get into trouble. Koichi acknowledges that she is right, although his power proves to be handy during the fight against Octoid.
Although Koichi's carefree attitude was a problem, Kazuho continues to feel something for him, and this caused him to be involved in the police investigation about trigger distribution. It turns out that Koichi is invited by the Mad Hatters to participate in a mixer where to meet other girls. Moved by jealousy, Kazuho follows Koichi on his way to the mixer, casually meeting the hero Midnight, who explains that one of the girls is suspected of trafficking with trigger. Midnight asks Kazuho for help, and using his influence, he can both participate in the mixer in disguise and with fake names.
Thanks to her costume Koichi does not recognize her. After a series of events, Rin Yaritezawa, the girl considered suspicious of being the trigger dealer, falls for Koichi, i, which awakens not only Kazuho's jealousy, but also Hina's, the real trigger dealer. Hina tries to drug Koichi's drinks with trigger, but due to a number of circumstances, the drinks that she offers to Koichi end up being drinks for other customers of the bar, resulting in them starting to lose control over their quirks. Midnight uses his Somnambulist Quirk to put everyone to sleep, and arresting Hina in the process. The mission makes Midnight and Kazuho become friends, to the point that Midnight gives Kazuho her cell phone number to call her if she need help.
Captain Celebrity's Farewell
By the end of December, the Marukane Performers decide to celebrate Christmas together in Marukane. Kazuho enjoys the festivities along with Koichi, Makoto, Captain Celebrity and many others. When the party is over, Kazuho congratulates Captain Celebrity for the good news that he will be a father and will be able to return to the United States.
After the party, the Little Sisters of Saint Lila's Academy get into a taxi, but from the sky appears a flying creature that takes the taxi, with the girls inside. Captain Celebrity goes out in pursuit, but just when he is going to reach them, the creature explode. Fortunately, Captain Celebrity manages to rescue the girls on time and unwounded.
This feat made Captain Celebrity's probability increase, and on the occasion of his return to the U.S., Makoto decides to organize a spectacular farewell party at the Tokyo Sky Egg, inviting numerous professional heroes for the occasion. Kazuho, as well as the other members of the Marukame, are surprised to learn that they will also be part of the Show. When Kazuho starts discussing that with Miu and Yu, they freak out when they realize the size and notoriety of the event in which they are going to participate.
During the weeks leading up to the event, Kazuho prepares intensely with his teammates: train for the performances, study the dances choreographies, organize the costumes, etc ... she is so focused for the show that she hardly pays attention to anything else, even ignoring Koichi.
After several weeks, the farewell party of Captain Celebrity takes place. The event has a great success among the attendees, who enjoy the various acts, the participation of the heroes, etc ... Kazuho and his companions go out to dance and perform for the public.
However, that celebration is suddenly interrupted when the Tokyo Sky Egg is attacked by five creatures equal to the one it attacked during Christmas, known as Bombers. Captain Celebrity comes out to face each other, but the Bombers damage the structure, and Captain Celebrity must use his strength to prevent the building from collapsing with thousands of people inside, being defenseless against the Bombers' attacks.
That attack had been orchestrated by Number 6, an agent of the Villain Factory, a criminal organization responsible for Trigger's traffic and several villain attacks in recent months. Number 6 had also been responsible for the attack during Christmas, made to discover some weak point in the Captain, and had meticulously planned that attack to assassinate him.
Nonetheless, thanks to the intervention of Koichi and the heroes who were there, they manage to defeat the Bombers. Frustrated because his plans has been dismantled, orders the last bomber to self-destruct in a powefull explosion, making the Tokyo Sky Egg begins to fall down. Fortunately for everyone, All Might arrives on time to save everyone, landing the Tokyo Sky Egg dome safely.
After thwarting the attack, Kazuho and everyone of the Marukane Performers, from the performers to the staff, decide to stay and help, are handing out for free official merchandising of the event (hoodies, food, drinks, ...) among people to help them feel better. Number 6 makes a last desperate attempt to cause the greatest number of victims, but his plan fails again thanks to All Might, and this time the villain decides to retire.
During the days following the attack, Kazuho helps take care of Captain Celebrity, who is in the hospital recovering from the serious injuries he suffered from the Bombers. After two weeks, Captain Celebrity manages to recover enough to beign able to return to the USA with his family. Aat the international airport, the Marukane members meet to say goodbye to them. To the surprise of Kazuho, Koichi and the Captain, Makoto announces that she is also leaving for the United States to attend a prestigious university and continue her studies.
That night, Koichi returns along with Kazuho to his penthouse. Once there, they start talking about Makoto. He talks about Makoto's departure and how well she handled the press, but Kazuho thinks she could have given Koichi more credit. Koichi thinks that some credit would be fine, so tells Kazuho that if she wants she can praise him, but a flustered Kazuho replies that he can't ask for it like that.
Looking for a purpose
Three years have passed since Koichi became a Watchman. Throughout that time, Koichi has been protecting Naruhata from malefactors and helping local people, to the point that he is considered a local hero. During all that time Kazuho has been helping him with his vigilantism tasks. However, things are starting to change.
To Kazuho's surprise, Koichi confesses that his days as The Crawler is about to end. Once he gets a job, he'll have no business playing hero anymore and stop being a vigilante. His words surprises Kazuho.
In Marukane, things are not going well. since she went to the United States, former manager Makoto has been successful and has become a celebrity in the country. However, with her departure, the success of the Marukane Performers began to decline progressively. The Narufest is becoming less and less popular, and the Marukane's directive is been slashing their budget. Gradually its members began to leave, nowadays too busy with jobs or studies, to the point that only Kazuho, Miu, Yu and the Sisters of Saint Lila's Academy remains.
Because their last show did not have much audience, the remaining member have gathered to suggest ideas that can boost attendance, but they don't find the right solution. Miu does not take the meeting too seriously, commenting that she is now interested in finding a boyfriend during high school. When mentioning this, she asks Kazuho how her relationship with Koichi is going, which makes her very nervous. She tells Kazuho that she risks that Koichi'll move on and taking an interest in another girl. Yu tries to stop his sister, although she acknowledges that many things have changed since then, and tells Kazuho that she should think about his relationship with Koichi.
At that time, their new manager Nomura enters the meeting room and communicates the bad news. Despite his efforts to try to convince them of the opposite, Marukane's executives have decided that next month's Narufest will be the last. This saddens the girls, although it was somewhat predictable, and they decide to end the meeting.
Kazuho walks back to the penthouse, sad because the group is going to break-up soon. While walking, she thinks about Miu's words, and decides to cook curry for Koichi. Upon arriving the penthouse, she is surprised to find that Makoto was there, cooking curry. After dinner, Makoto tells Koichi and Kazuho that she has decided to return to Japan, despite her success in the United States. Makoto asks how things are going with Narufest. Kazuho tries to answer her but Koichi does it first, saying it is rollin 'along just fine. Kazuho decides to play along.
Then Kazuho decides to leave the penthouse, but she barely steps away when she regrets not telling Makoto the truth. When she turns around, she sees Makoto hugging Koichi and eavesdrops their conversation. Makoto confesses his feelings for Koichi, who is surprised by her's confession and doesn't know what to answer. Although Makoto would like her feelings to be reciprocal, she decides to give Koichi time to think well about her answer, as she also takes into account Kazuho's feelings. Makoto is sure that Kazuho is in love with Koichi too, so she gives him time to figured out how he and Kazuho feel about it before he make his decision. The whole conversation leaves Kazuho confused and nervous.
That conversation makes Kazuho evasive with Koichi the next morning. At night, she understands that she needs to put her thought together and confess her feelings to Koichi. But when she compares with Makoto, Kazuho realizes that she is better than her in any aspect. In addition, she knows that her success is thanks to Makoto. Depressed, she starts watching online videos of when she started performed in the streets like Pop☆Step being still very young.Tthe clip of her first performance gives her gives her the courage not to give up.
The next day, after talking with her companions on how to organize the last Narufest, Kazuho decides to perform a solo performance at the streets. She can barely sing as three thugs appear and mocking her. Fortunately, the manager Nomura also appears and takes her out of there before there are more problems.
The two go to a cafe, where Kazuho explains to Nomura about her solo project. Kazuho explains that she tries to craft a future for herself beyond the Narufest. Nomura asks Kazuho to let him listen to her song, getting too excited for its lyrics and composition, so he decides to help Kazuho and offers himself to be her producer, so everyone can listen to her song. When they leave, they meet again with the trio thugs. Their leader attacks them, but Nomura manages to defeat him and restrain him with a hold. Nomura tells him that he is a hero, and he shows his hero license to prove it.
The next day, per Nomura's advice, Kazuho tries to convince Koichi to obtain his hero's license. She tells that he could get his license while still doing his day job. Koichi dismisses the idea because it would be too difficult for him and asks her why she is so interested in what he does to which she denies that she does. While on the topic of the future, Koichi tries to talk to her about another matter, but Kazuho apologizes because she has to get to a meeting at Marukane. She promises that she will hear him out later. After the meeting, where everyone agrees to contact the FeatherHats members for the last Narufest. Kazuho and Nomura leave quickly to carry out a street performance. Kazuho to sing one of her songs, obtaining great success among passersby.
After this, Kazuho and Nomura celebrate the success of their performance at a bar,where the manager tells him that his real name is Rokudo Nomura. After finishing, while they walk the streets, Nomura confesses that he wants to be her producer and do everything fot her. Kazuho feels flattered by his words, but she tells him that her songs are for herself and give herself courage. She leaves giving thanks to Nomura for everything.
Kazuho feels sure of herself and prepares to confess he feelings to Koichi, but suddenly loses that confidence when he shows her the tie Makoto gave him for the interview, and leaves immediately without saying anything to Koichi. Confused, he tries to ask Kazuho what happens, but she had already left. At her home, Kazuho locks herself in her room and phones Nomura. Crying, she apologizes for rushing off earlier and tells that she needs him to be there for her. Nomura replies that he is there to help her.
The two agree to meet in a cafe, where Kazuho tells him that she still does not have enough confidence in herself. Nomura responds by telling her the appropriate answers to encourage her, and suggests a change of scenery. he tells her that she should come and visit his own "secret hideout", taking her to a rundown building. Nomura apologizes for the place, but Kazuho doesn't mind because she knows someone who lives in a similar dump.
Then, Nomura takes Kazuho to the basement and asks her to enter a room. Thinking that there is a studio there, Kazuho does it, only to see a dark room and hear a strange buzz. As she walks into the room, the manager Rokudo Nomura decides to stop pretending, revealing himself as villain Number 6. He pushes Kazuho in and locks the door behind her. It's dark, but she quickly finds a pile of corpses in the corner, and that the strange buzz came from a swarm of bees....