When Izuku got back to the dorms she was immediately found with a hug from her boyfriend who said "We heard what happened Izuku, it's not..." Only to be interrupted by Izuku saying "Yes, it is. I'm a bad guy, aren't I? I'M A BAD GUY!" Izuku said saying that last part while crying "No, you aren't You're an angel born of heaven, always was and always will be." Katsuki said, only for Izuku to say "No, I'm not. Here I am crying about my problem instead of cheering you on for your provisional license exam." At first Katsuki looks shocked at that answer then he smiles and says "You see stuff like that, caring about someone else's problem while you're having a meltdown is exactly why you're an angel." Only for Izuku to realize Katsuki had a point and say "Really?" "Really." Katsuki said, only for Izuku to say "You're the best boyfriend ever" Only while scooping her into the air he said "No, you the best one ever." This got Izuku to laugh "There's my Izuku." Katsuki said and then they (Katsuki and Izuku) kissed.
Later the class (class 1A) are sent to Nabu Island on a Hero Work Recommendation Project, where they (the class) will act as their own agency without any aid from the teacher(s). At Nabu island acting as a hero agency, Ochaco gets a call from a little girl (Mahoro) claiming to have lost her little brother (Katsuma), Izuku, Kyoka and Ochaco go to find Katsuma only to find he's not lost and it was a test set up by Mahoro who goes on to scold Izuku for taking so long. "You toke an hour to find him, if this is what heroes are like then I don't like them." "I don't care, as long as he's (referring to Katsuma) safe than I'm happy." Izuku said then smiled then glowing smile of hers, touching Katsuma's heart who was delighted to see it but not Mahoro's who wasn't delighted to see it. Later on, at night Izuku is training her quirk and her magic where she is found by her boyfriend "You're getting better at this." He says, only for Izuku to say "Not as good as you are though." They (Katsuki and Izuku) then kissed only to be interrupted in the middle of kissing by Katsuma saying that "A villain has appeared." Izuku is shocked while Katsuki is excited, only to find a giant mantis. Katsuki tries to blind the thing only to find something wrong and stops. That's when Izuku arrives and sees the mantis go right through Katsuki who generates a huge explosion that knocks Mahoro from her hiding place which causes the mantis to disappear. Conforming Katsuki's suspicion that the mantis was just an illusion (Katsuki came to that conclusion when he saw the mantis had no shadow). Katsuki then figures out the creature was made from Mahoro and goes to punish not only her but Katsuma as well but stops when Katsuki sees Izuku "You two are so lucky I'm trying to be good for my girlfriend." Amazing Izuku who fell more in love with him than she already was with Katsuki and that didn't seem possible considering that she was fully in love with him.
The next day Katsuma apologizes about Mahoro to Izuku with Katsuki overhearing them (Izuku and Katsuma). Katsuma explains that "You see Mahoro was doing that to get me to drop my dream of being a hero, she believed that no one would come but she was wrong. You came, both times in fact." "You have an Edgeshot pin, do you like heroes?" Izuku asks, only for Katsuma to say "I admire heroes and I want to be one even though my quirk isn't suited for combat." Making Izuku realize Mahoro doesn't hate heroes, she just doesn't want her brother getting hurt which reminds Izuku of her mother. Izuku says "Anyone can become a hero, as long as you put your focus into putting in the effort." Katsuki overheard everything.
Slice attacks the harbor with Katsuma and Mahoro overhearing and seeing it. They contact 1A headquarters and explain what's going on, only to get Katsuki who doesn't believe them at first until he sees Izuku and decides to believe them. Only for the pone to get cut off, Izuku having overheard their (Katsuma and Mahoro) location goes after them all (Katsuma, Mahoro, Katsuki and Izuku) unaware that the one behind the phone cutting off is another villain, Chimera and that there's a villain (Nine) going after Katsuma. Katsuma and Mahoro run away back home to which they run into Nine who has destroyed their home. Nine uses his quirk (which is one of many) that can let him see another person's quirk and sees that Katsuma has the quirk Nine needs. Before he can steal it Izuku arrives and recuses the kids using One For All, using said quirk she caring the kids runs away from Nine and into the forest to their (Katsuma and Mahoro) safety. That's when Izuku fights Nine (who has followed her) using Lasor Shoot but Nine uses Air Wall quirk to create a barrier to defend himself with. Izuku retreats after Nine uses his Bullet Laser quirk to fire laser beams at Izuku. Izuku realizes that 'He's (Nine) got the same quirk as All For One.' she thinks and attacks using Delaware Smash Air Force but this too is blocked by a barrier made from Air Wall and Nine retaliates by using it to push a gust of wind at Izuku. Izuku then activates Full Cowl at twenty percent but is outmatched by Nine's power. Using the scanning quirk, Nine sees Izuku has an interesting quirk but it doesn't include the wand much to his surprise and non-interest as he doesn't care about the wand and only cares about One For All and tries to steal it but is stopped somehow which temporally immobilizes Izuku. Nine is surprised that he can't steal One For All and thinks it has to do with the fact it is multiple quirks in one. Disappointed he can't steal One For All, Nine blasts defenseless Izuku which slams her into a nearby hill. Mahoro and Katsuma try to help Izuku, but he orders them to flee. Nine proceeds to shoot a purple laser at Izuku's chest, wounding him. Frightened, Mahoro uses her Quirk to project a cartoony version of the wounded Izuku to notify everyone. Before Nine can dispose of Izuku, Katsuki arrives and engages in combat with Nine, but even he, alone, is no match for Nine and his multiple Quirks. Katsuki manages to outsmart the villain and is about to attack him up close when Nine activates his Hydra Quirk and pins down Katsuki. Izuku manages to recover and attacks Nine. As Izuku is close to landing a blow at Nine, he uses his original Weather Manipulation Quirk to summon a massive lightning strike to zap Izuku and Katsuki, severely injuring them in the process. While at the same time, causing a major blackout throughout Nabu Island. With Izuku and Katsuki down, Nine goes after the children but then, he suffers from his cell degeneration disease and is unable to continue fighting. Slice arrives to help Nine and attempts to take Katsuma before Koda uses his Anivoice Quirk to summon a swarm of crows to blind the villains while Mezo, Tsuyu, and Ochaco rescue the wounded Izuku and Katsuki and the children. Nine orders Slice to chase them but she assures him that they cannot leave the island and what they (Nine and Slice) must do now is withdraw so that Nine can recover. With the kids gone and Nine in pain from his illness, Slice fires a flare gun to call all their allies to retreat.
Later at night, Class 1-A regroups and holds out in a factory with all the civilians that they've managed to save and providing humanitarian aid to the local residents. Mummy was captured, locked up, and chained inside the machine room, but he refuses to talk to any of them after they questioned the villain. Momo and Denki are currently working on maintaining essential supplies. Ochaco goes into the room where other civilians are being healed by medical staff from the hospital clinic with healing Quirks. Izuku and Katsuki are both unconscious and the Doctors can only use their Quirks to close their wounds, but they cannot treat them any further because they've suffered so much damage that they need to be sent to a hospital in the mainland. Mahoro and Katsuma then come into the room and they say that he can help using his Cell Activation Quirk to heal both Izuku and Katsuki. The doctors appreciate his help and invite him to heal both heroes which Katsuma does In another room, Class 1-A holds a meeting to discuss how to deal with the major threat from Nine and the rest of the villains. Momo created a drone to send an SOS out to the mainland but won't arrive for six more hours. They are trying to figure out what the villains are after when Katsuma and Mahoro enter the room and Katsuma reveals that "I'm the target for the villains, since Nine wants to steal my Quirk." Some students suggest helping the boy escape to thwart the villain's plans, but Shoto advises against it as they (the villains) could kill the inhabitants of the island in retaliation. Katsuma then offers to surrender himself to Nine to save everyone but Izuku appears, having fully recovered after Katsuma healed him, and dissuades him of his idea by telling him "You have an amazing Quirk that you should never give up." Katsuki also enters the room fully healed and tells everyone that "The only thing to do is to crush the villains." Izuku devises a plan of action for the class. The plan is to relocate all the civilians to Mount Shiroyama in the smaller island where the ancient castle is located, it can hold all of the residents in the large cave safely. This way, the villains only have one route to get to Katsuma and everyone has an escape route if needed. The heroes will engage the villains using the terrain to their advantage and spit the villains apart. Mashirao, Kyoka, and Mezo will personally guard Katsuma and Mahoro while the civilians are holding out inside the cave protected by Koji, Rikido, and Toru. That when Shoto questions "How are we going to deal with Nine and his multiple quirks?" Izuku notes that "Nine can only use his Quirk for a limited time due to the illness he is suffering, so the plan is to have everyone attack in waves to make sure the villain uses his quirk all the time until he has reached his limit and hold out until reinforcements from the mainland arrive."
With the villains approaching the ruins, the heroes begin their assault on the villains with a pre-emptive strike. Yuga attacks first using his signature move, Can't Stop Twinkling: Supernova, to fire a massive laser bombardment at the villains. While Nine blocks the attack with his Air Wall Quirk, Slice, and Chimera break away from the blast, unaware that they are falling right into their trap. Momo reveals two massive cannons she created last night with the last sources of her Creation Quirk and shot at the villains, which cause Slice to collapse in an underground cavern and Chimera plunging into a nearby waterfall. With the villains separated, Hanta and Ochaco commence their assault on Nine. Hanta uses his Tape Quirk to throw huge boulders at Nine supported by Ochaco's Quirk, Zero Gravity. Nine deflects all of their attacks using his Air Wall Quirk for defense and his Bullet Laser Quirk for an offense. Ochaco continues to use her Quirk to make more floating boulders for Hanta to throw at Nine, but the villain is still not stopping, so Hanta, Minoru, and Ochaco retreat to a trap they prepared and caused a massive rock slide with Minoru using his Ultimate Move, Super Grape Rush, to make the rocks stick together even harder to bury the villain. However, Nine is able to break free easily, knocking Minoru out of the battle. Momo and Yuga intervene and engage Nine but the villain defeats both of them. Izuku and Katsuki engage Nine but they aren't strong enough to take down the villain as Nine uses his Air Wall and Bullet Laser Quirks to defend and attack at the same time. Hanta attempts to help out, but he is defeated after Nine uses his Bullet Laser Quirk to blast him. Ochaco tries to make Nine floats but she gets knocked out by his Hydra Quirk. Izuku and Katsuki fire back against the Hydra Quirk with a combination of Delaware Air Force, Raspberry Rocket and AP Shot but the quirk is too much and takes them both down. As the villain's about to defeat Izuku and Katsuki, Nine has reached his limit and starts to reel in pain from his illness. Izuku and Katsuki seize the opportunity but Nine activates his life-support to take a heavy dose of empowering drug and goes beyond his limit, summoning a massive lightning strike that seemingly vaporized Izuku and Katsuki. Meanwhile, in the underground cavern, Fumikage engages close combat with Slice in his Black Abyss with Mina providing support using her acid quirk. Despite using the darkness to his advantage, Fumikage proves to be unmatched for Slice and her swift combat agility. Fumikage makes an opening for Mina to use her signature move, Acid Shot, to destroy much of Slice's hair. Fumikage attacks with Dark Shadow, but Slice retaliates by using her Quirk to fire multiple barrages of sharp needles at Dark Shadow and Mina. Mina attempts to dodge all of her attacks, but she gets wounded in the process. Enraged, Fumikage goes berserk and his Dark Shadow Quirk intensifies to become massively monstrous and viciously attacks Slice. Slice attempts to shoot her hair needles at the ceiling, but she is defeated by Fumikage after Dark Shadow grabbed her. However, the cavern collapsed on top of them. The sunlight from the sky nullifies Dark Shadow as Fumikage uses his body to shield the wounded Mina while the cavern buries all of them under piles of boulders. At the waterfall, with Chimera alone, Tenya, Tsuyu, Eijiro, and Shoto attacks the villain. Tsuyu drags Chimera into the water before Shoto freezes it, but it isn't enough to stop the villain. Eijiro and Tenya attack him with a series of kicks and punches while Shoto fights back with fire and ice attacks using his Half-Cold Half-Hot Quirk. At first, Chimera seems to be able to repel all three of them easily until he feels his body being paralyzed. It is revealed that Eijiro and Tenya were attacking the villain using the special toxin mucus from Tsuyu's Frog Quirk. Chimera uses his Quirk to transform and grow his body bigger, nullifying the toxin. The villain fires a massive burning blast at the four of them. Shoto attempts to make an ice wall to block it but it's not enough, forcing the four heroes to flee to avoid the fire. Pinned by Chimera, Shoto devises a plan: Tenya uses his Quirk: Engine to distract Chimera using Recipro Turbo, while Eijiro and Shoto sneak from behind using the same method they had used to save Katsuki in Kamino. Chimera notices them and fires his burning breath to blast them. Eijiro uses his Hardening Quirk to activate his signature move, Unbreakable, to take the full-frontal hit from the laser before he loses consciousness, giving Shoto the opportunity to strike. After Chimera used up his fire beam, Shoto manages to get on top of the villain with Tsuyu restraining the hands using her long tongue and Tenya holding the tail to the ground. Chimera manages to defeat Tsuyu and Tenya and knock both of them out before Shoto defeats the villain by activating his Quirk to reach sub-zero temperatures and freeze the villain inside out before passing out from the cold temperatures in his body. At the same time, in the mainland, Hawks questions Katsuma and Mahoro's father who regained consciousness and retells everything that happened to him and how Nine, stole his Quirk. Hawks receives a call from the Public Safety Commission who informs him that a fisherman found a drone that contains a message saying that villains have attacked Nabu Island. Realizing that Class 1-A is at Nabu Island and engaging Nine and the villains alone, Hawks flies over to the island as fast as he can while contacting U.A High to send in reinforcements. Meanwhile, the situation for Class 1-A is growing dire as Nine was proven to be too powerful for all of them. Mashirao, Mezo, and Kyoka flee with Katsuma and Mahoro to the escape route in the caves. Mezo takes the kids away while Mashirao and Kyoka ambush the villain first to hold him back but they are smashed by the Hydra Quirk. Nine later catches up to Mezo and attacks him using his Bullet Lasers as Mezo protects the kids. Mashirao and Kyoka catch up to attack Nine with Mezo tackling with his Dupli-Arms Quirk but the villain blasts all three of them away, defeating them. Izuku saves Katsuma at the last possible instant. Nine holds Mahoro hostage to demand Katsuma to surrender his Quirk or he will kill his sister. Before Nine can steal his Quirk, Izuku and Katsuki enter the fray to save Katsuma and Mahoro, revealing that they survived the lightning strike using Denki as a lightning rod to absorb the lightning. Izuku and Katsuki gain the advantage after Nine is reaching his limits of using his multiple Quirks and overwhelms him with a combination of Detroit Smash, Magic and Explosion. On the verge of defeat, Nine uses the entire empowering drug in his life-support system which amplifies his Weather Manipulation Quirk to the maximum and summons a massive fire tornado and lightning storm and begins to destroy everything on the island. Izuku boosts his Quirk to reach 100% and uses Detroit Smash with Strawberry Smash while Katsuki uses Howitzer Impact but the two aren't strong enough to stop Nine and gets obliterated by the Weather Manipulation Quirk. Mezo manages to regain consciousness and uses his body to shield Katsuma and Mahoro from falling debris as the firestorm causes a cave-in, trapping Koji, Rikido, and Toru along with the civilians in the cave. Izuku and Katsuki manage to survive but they are severely wounded. Nine proceeds to decimate them with his Bullet Laser and uses his Hydra to start crushing them to death. With the entire class down and wounded, Izuku makes one last final gamble; to transfers One For All to Katsuki. "Katsuki, I'm going to transfer One For You to you." Izuku said, only for Katsuki to say "What but it's your quirk." Only for Izuku to say back "I won't be if he wins, don't worry you'll just give it back afterwards." Katsuki knew she had a point and agreed. They (Izuku and Katsuki) kissed with Izuku using the kiss to spit into Katsuki's mouth. Before he could question it she forced him to swallow it. "There now it's yours, remember to spread it evenly around your body." Izuku said, infuriated with this Nine attempts to kill them by summoning another massive storm on the island, destroying much of the island's infrastructure. Katsuki boosts up to reach Full Cowl - 100% and together with Izuku, they use Detroit Smash to stop the tornado. Nine is just shocked by what he just witnessed, but he still refuses to give up on fulfilling his dreams and engages Izuku and Katsuki in a intense combat, releasing all his Quirks at their maximum power. After a lengthy fight, Izuku and Katsuki finally manage to defeat Nine once and for all using the Explosion Quirk combined with St. Louis Smash at 100% and Strawberry Blast, effectively ending the threat but the ember left by One For All sparks out, leaving Izuku Quirkless once again. Both Katsuki and Izuku pass out from their injuries and exhaustion. Later Katsuki transfers back One For All to Izuku