Ectoplasm/Synopsis

History
In the past, a villain took Ectoplasm's legs. He now wears a proper prosthetic when in civilian clothes and sports a special lightweight battle prosthetic while in his costume.

Entrance Exam Arc
Ectoplasm first appears watching the Entrance Exam's practical portion. He is surprised when Izuku Midoriya uses his Quirk to destroy the giant villain bot.

U.S.J. Arc
The League of Villains, led by Tomura Shigaraki, assaults the Unforeseen Simulation Joint with a large force of villain with the goal of killing All Might, attacking the students of Class 1-A in the process. With the help of his classmates, Tenya Ida manages to escape to call for backup.

Ectoplasm is one of the pro heroes who arrive at U.S.J with Tenya as reinforcements, arriving in time to save Class 1-A from the siege by the League of Villains. A group of villains attempts to attack them but Present Mic repels them with his Voice. Then Ectoplasm uses his Quirk to exhales a wave of ectoplasm that transforms into an army of Clones that beat the villains back and knock them.

Realizing that his plan had failed, Tomura managed to escape with the help of Kurogiri, despite the heroes' attempts to prevent it. With the leader of the villains on the run, the teachers scatter to defeat to defeat the remaining criminals and rescue the students. Ectoplasm takes down several more villains and rescues Denki Kaminari, Momo Yaoyorozu, and Kyoka Jiro.

U.A. Sports Festival Arc
Ectoplasm watches the U.A. Sports Festival alongside the other teachers.

Final Exams Arc
Ectoplasm is present for the faculty meeting where the teachers agree to change the practical portion of the Final Exams. He is placed against Tsuyu Asui and Fumikage Tokoyami to take advantage of Fumikage's weakness at close range. He and the other teachers explain the changes to the exam to the students of Class 1-A.

Ectoplasm faces Fumikage and Tsuyu in the second battle inside a large labyrinth type building. Fumikage and Tsuyu start at the center of the structure and Ectoplasm spawns several of his clones around them. He warns them that he and the other teachers will do their best to crush the students. The students manage to flee into the upper levels of the building, but Ectoplasm keeps his clones in hot pursuit.

Although Ectoplasm's clones manage to overwhelm Fumikage a few times, Tsuyu's support allows them to destroy twenty-eight of them. The students reach the vicinity of the escape gate where the real Ectoplasm is waiting. He compliments the tandem for defeating his clones but asks them if they can deal with his next attack. Ectoplasm uses Giant Bite Detention, a move that creates a giant clone of himself and traps the students inside it.

Immobilized, Fumikage orders Dark Shadow to escape in a last-ditch effort. Ectoplasm intercepts it and attacks with a flurry of kicks. Dark Shadow is unable to get past Ectoplasm with hand to hand combat and shortly retreats. They clash one final time, and Dark Shadow manages to handcuff Ectoplasm in a sneak attack. Tsuyu swallowed the handcuffs beforehand and gave them to Dark Shadow during its retreat. Having passed the exam, Ectoplasm releases the students from the giant clone and commends them on their clever synergy.

Provisional Hero License Exam Arc
Ectoplasm, Midnight, and Cementoss join Shota Aizawa in his homeroom class to announce that Class 1-A needs to develop super moves. They move to Gym Gamma, where Ectoplasm creates twenty clones for each student to fight in order to further develop their quirks and eventually create special techniques. This training is meant to prepare the students for the upcoming Provisional Hero License Exam. Ectoplasm uses Tenya's Recipro Burst as an example of a super move.

Ectoplasm easily defeats Mashirao Ojiro during a sparring match. He tells Mashirao he moves predictably and they need to work on his fighting fundamentals. Mina Ashido tries further the range of her acid attacks and Ectoplasm advises her to do so by forming her hands in the shape of a nozzle. Ectoplasm challenges Momo Yoayorozu to create two things at once with her Quirk, and she does so with ease. Katsuki Bakugo excels during the training and even manages to destroy one of Ectoplasm's clones before demanding he make another.

Ectoplasm catches Izuku Midoriya staring off into space and hits him. Izuku explains he's struggling to develop a technique because of the injuries to his arms. Ectoplasm agrees that Izuku's Quirk is too inconsistent and if he doesn't have a fixed fighting style than he needs to focus on developing it for the day. Ectoplasm also supervises Rikido as he eats sweets and tells Ochaco Uraraka to focus while levitating herself.

U.A. School Festival Arc
Due to the incidents that have occurred in recent months, the Police Force's Commissioner General requests Nezu to cancel the U.A. School Festival, but the principal manages to convince him otherwise after assuring him that security measures will be increased. For this reason, Ectoplasm, Hound Dog and Snipe, Hound Dog are put in charge of security.

Shortly before the festival starts, Ectoplasm is informed that a student has left and has not returned, prompting Ectoplasm to look into the situation. However, Ectoplasm is soon informed by Hound Dog that there is a disturbance and requests to borrow five of Ectoplasm's clones, which Ectoplasm allows.

Upon reaching the place of origin of the disturbance, they meet Gentle Criminal and La Brava as Gentle declares his surrender. Ectoplasm recognizes Gentle from his online videos, and Hound Dog angrily asks him what their intentions are and what has happened. Soon after, Izuku arrives at the place and Izuku explains to the teachers that Gentle was trying to pull a prank on U.A and and they got into a small dispute but that everything is fine now.

Hound Dog is suspicious about his explanation, since both Izuku and Gentle are dirty and scratched, but reports that the festival to continue can continue without issue, and the teachers take Gentle and La Brava to the police station. After Gentle is escorted away, one of the Ectoplasm clones inform Izuku that All Might is worried about him and there is less than an hour left for Class 1-A's performance to start. Izuku panics after remembering he left his bag of items for the festival back in town and needs to get it and the Ectoplasm clone comes along with Izuku.

They get the stuffs back and return to the festival on time. The Ectoplasm clone suggests to Izuku that he cleans up his face before going on stage as his dirty face will worry the audience but he will still make it in time. In the end, the festival proceeds without incident. After Class 1-A performance, Ectoplasm sees All Might and Hound Dog scolding Izuku for his recklessness before letting him go to have fun at the festival.

Joint Training Arc
The next after the Joint Training Battle between Class 1-A and Class 1-B, Ectoplasm and other teachers are in the meeting room discussing Hitoshi Shinso's transfer to the Hero Department. They decide that it will definitely be happening.

Endeavor Agency Arc
By the end of December, Ectoplasm is in the Conference Room with other U.A. teachers discussing the requests of the Hero Public Safety Commission. The Commission demand that all students from all hero high schools to undergo practical field training, restarting the Hero Work-Studies with the main goal the students learn how to cope the villain organizations that are beginning to rise.

Ectoplasm is sure that the terrible incident that occurred a few days ago in Deika City worries the Commission and has influenced that decision.

Paranormal Liberation War Arc
By the end of March, thanks to the police investigations, and the information leaked by Hawks, who was acting as a spy, the Hero Public Safety Commission organize the Heroes and the Police Force to take down the Paranormal Liberation Front. Ectoplasm is part of the hero force led by Endeavor in charge of assaulting the Jaku General Hospital, where Nomus are created and where Tomura is hiding, and arresting its current board chairman, Dr. Kyudai Garaki, who is an ally of All For One.

When the raid begins, Ectoplasm is part of a team in charge of evacuating patients, medics and other civilians to a safe place, while another team faces the Nomu and reaches the underground secret lab. Unfortunately, Tomura awakens and uses his Decay to completely disintegrate the hospital, killing dozens of heroes in the process.

Tartarus Escapees Arc
In the aftermath of the Paranormal Liberation War, All For One has escaped from Tartarus, and proceeded to break into several more maximum security prisons, liberating the inmates. Due to the chaos inflicted by Gigantomachia and the mass breakout of prisoners, the whole country entered a state of total chaos and anarchy. In addition, many heroes resigned and called it quits because of the massive criticism of their work, and the destruction spreading unchecked.

When Izuku goes rogue, Class 1-A goes off to search after him, while Ectoplasm and the other remaining U.A. teachers are stationed at the newly fortified U.A. High, acting as a safe base for evacuees.

Once Izuku and Class 1-A returned to the heavily fortified U.A., they are then confronted by a group of protestors within the school demanding Izuku not be let in. The civilians say they know he is the rumored boy Tomura is after and after they were convinced U.A. would provide them sanctuary, allowing what they consider a "ticking time-bomb" is a horrible idea.

With no one seemingly listening to reason, Ochaco floats her way over the crowd and jumps up onto the U.A. building with a microphone, addressing herself to the people. She tells everyone to take a closer look at Izuku for he wishes to fix everything despite knowing he could be attacked at any minute. Sure enough, the people start calming down, and everyone, including Ectoplasm, listened to Ochaco's speech. The mood in the civilians realized what they've done instead of contributing to their society, and resolve to do the same for the heroes. Outside U.A., Ectoplasm asks Endeavor, Hawks, and Shoto if they heard Ochaco's speech before letting them in, saying that everything is fine for now.

U.A. Traitor Arc
While Ectoplasm continues to do his duties, he and the other U.A. staff learned devastating news that Yuga Aoyama from Class 1-A and his family were captured by Izuku and he is revealed to be the U.A. traitor Present Mic mentioned a year ago, responsible for the U.S.J. Incident and revealing the location of the Quirk Training Camp. In the U.A. A.V. Room, the Aoyama Family are interrogated by All Might, Detective Naomasa, and the U.A. staff, learning Yuga was Quirkless and received his Quirk about 10 years ago from All For One, so his family was forced into his debt. However, all of Class 1-A had already heard the news and are devastated, bluntly refusing to back down.

After interrogating them on information regarding All For One, Izuku speaks up as he recognized Yuga's troublesome situation and had no malicious intentions in his actions, so wants him to help them and prove he can still be a hero. The rest of the class believes this as meaning they can use Yuga to deceive All For One, but Naomasa reminds them that it is still very unlikely that could work. Just then, Shota Aizawa, listening in on a tablet, informs everyone that he has an idea, which they all listen to after covering the Aoyama Family's ears. Nezu says that it seems possible, and All Might adds that it'll be up to how well "he" can handle it, as Naomasa escorts the Aoyama Family back to their HQ, telling everyone not to say a word to anyone else about the plan. With everything settled, the police takes Yuga and his family away for further investigation, leaving Class 1-A to look on sullenly.

By weeks end, Nezu announces to the civilians that Tomura will make his big move in 4 days, with Class 1-A giving their thanks to everyone at the entrance, and Izuku saying he’s had more than enough time to clean himself up, with them all ready to head back out. Ectoplasm watches Class 1-A each say goodbye to their family members and the civilians before moving out of U.A. for good.