Ectoplasm

Ectoplasm (エクトプラズム) is a Pro Hero and member of the U.A. High School faculty, who teaches mathematics.

Appearance
Ectoplasm is a slender man with dark hair and glasses. He has large blank eyes and trademark exposed teeth. He also does not have any legs, due to having lost them in the line of duty, so instead he uses artificial limbs.

In his hero costume, Ectoplasm wears a tan trench coat that covers most of his body. Underneath is a skin tight, black suit with several gold  stripes rising up from underneath his trench coat and disappearing under his helmet. His helmet is black and with a gold jawguard that ends in a circle-shaped hinge joint where his ears are. Another frame comes from the hinge, going over his cheek bones and meeting on his nose.

Personality
Ectoplasm is a steadfast and unrelenting hero, which has made him highly popular. As a teacher, Ectoplasm desires the best from his students and isn't afraid to push them. He openly warned Fumikage and Tsuyu he would do his best to crush them during final exams. During which, he also told them he was looking for his students to shine under pressure.

History
In the past a villain took his 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.

Unforeseen Simulation Joint Arc
Ectoplasm is one of the pro heroes who arrive at U.S.J with Tenya Iida as reinforcements. They arrive to Class 1-A under siege by the League of Villains. Ectoplasm uses his Quirk to take down several of the villains and rescues Denki Kaminari, Momo Yaoyorozu and Kyoka Jiro.

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 Forced Internment Giant Bites, 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.

Hero License Exam Arc
Ectoplasm along with All Might, Cementoss and Midnight, were the repossessed by training class A and B students to develop their Quirks and special techniques before the provisional hero license test.

U.A. Cultural Festival Arc
For the U.A. Culture Festival, Ectoplasm and Ryo are put in charge of security. As Izuku and Gentle battle, Ryo and several clones of Ectoplasm have caught a whiff of Izuku and Gentle's battle. Hound Dog and the Ectoplasm clones have reached Gentle and La Brava, as Gentle declares his surrender.

Quirk and Abilities
Clones (分身): Ectoplasm has the ability to produce ectoplasm from his mouth and transform it into clones of himself. He can create up to thirty clones at once, and push his limit to thirty-six if he's feeling good. He can also produce a giant clone of himself, although this sacrifices his ability to produce normal sized ones for the time being. His clones can be defeated with a strong blow, but otherwise, only Ectoplasm can dispel them.
 * Forced Internment Giant Bites (強制収容ジャイアントバイツ): Ectoplasm shoots ectoplasm from his mouth and transforms it into a giant clone of himself. The giant Ectoplasm clone then overwhelms and traps the enemy with a huge bite. He first used this during final exams.

Equipment
High Density Weights (Final Exams Arc): Ectoplasm and the rest of the teachers use these bracelets to give themselves a handicap while they are fighting their students.

Prosthetic Legs: After a villain robbed Ectoplasm's legs, Ectoplasm wears prosthetic legs. In his hero costume, he switches to a lighter pair of prosthetic legs.

Final Exams Arc

 * Fumikage Tokoyami & Tsuyu Asui vs. Ectoplasm: Lose

Trivia

 * Ectoplasm likes karaoke.
 * Ectoplasm's head greatly resembles the helmet worn by Guy-Manuel de Homem-Christo, of the electronic music duo Daft Punk.

Quotes

 * (To Fumikage Tokoyami and Tsuyu Asui) "Less than ten minutes remaining...can you keep this up? I'm looking for...heroes who rise up and break through in the face of adversity."