Korosensei (real name Ryushi Korogane) is the homeroom teacher for Class 3-E of Kunugigaoka Junior High School, and the central character and main antihero of Assassination Classroom. He claimed to be responsible for creating the permanent crescent moon and said that he planned to destroy the earth after "teaching" Class 3-E for a year.
Prior to being a teacher, he was the master assassin known as the 1st "God of Death".
- Name: Korosensei, Ryushi Korogane (real name), Octopus, Grim Reaper, God of Death
- Origin: Assassination Classroom
- Gender: Male
- Birthday: March 13 (given)
- Star Sign: Pisces
- Classification: Artificially modified Human/Seraph hybrid, Class 3-E Teacher
- Height: About 3 m (9'10")
- Weight: 300 kg (661 lbs)
- Skin Color: Yellow
- Eye Color: White
- Alignment: Good
- Status: Active
- Class: SS-Class
- Powers and Abilities: Antimatter Physiology
- Weaknesses: Has a multitude of weaknesses shown below:
- When he tries to act cool, his weaknesses show.
- Surprisingly quick to panic
- He is petty
- His punches are weak
- He gets motion sickness
- Getting wet
- Time right after molting
- Time right after regeneration
- His body goes rigid when bathed in a special beam of light
- Heat fatigue
- He can't swim
- He sucks at hiding
- Grabbing all his tentacles at once makes him unable to move
- Notable Attacks/Techniques: Tentacle Attack, Energy Laser
- Voice Actor: Jun Fukuyama
- Attack Potency: Town level physically, higher with Energy Blasts
- Speed: At least Massively Hypersonic Travel, Combat, Reaction and Movement Speed
- Lifting Strength: At least Class 10
- Striking Strength: Class TJ
- Durability: Multi-City Block level. At least City level in Absolute Defense Form. However, he is immune to conventional weapons and lethal toxins
- Stamina: Above Superhuman (Can keep moving at Mach 20 for a few hours at least)
- Range: Standard Melee Range. Tens of Meters with tentacles and energy beams.
- Intelligence: Supergenius (Possesses a gifted mind which allows him to learn and understand complex knowledge in a matter of minutes. Extreme knowledge of all subjects as a teacher)
Korosensei had the appearance of a yellow bipedal octopus. He was about three meters tall and possessed a large, bulbous head with a large smile and small, beady eyes. He used two feelers as arms, with two fingers each, and utilized the rest of his tentacles to walk with. According to Korosensei himself, his nostrils are so small yet when discovered, it seemed that he had four eyes.
Korosensei wore a black academic dress, a small black square academic cap with a yellow tassel, and a large black tie with a yellow crescent-shaped moon on it.
The color of Korosensei's face changed depending on his mood, and is as follows:
- Yellow/Green = Happy, Emotionless/Neutral
- Yellow and Green Stripes = Mockery
- Orange with a Red Circle = Correct Answer
- Purple with a Dark Red X = Incorrect Answer
- Pink = Sleepy/Smitten
- Purple = Shock/Panic
- Blue = Sadness
- Red = Annoyance
- Black = Fury
- Pure White = Poker face, A mix of every emotion, or bored
- Mild-Yellow = Confused
It was revealed that he was raised in an environment "where everybody could easily betray one another to the point that one could only trust oneself". Through these hardships, he decided to become an assassin in order to survive. Despite he gained an apprentice, he only saw him as a tool for his goals, which caused the latter to finally betraying his master.
However, after meeting to Aguri Yukimura, he finally knew what compassion really was- becoming much more kind and compassionate. According to Aguri, if he was born in a peaceful country, his personality would be "someone a little perverted, with a good head but a few screws loose, petty about small things, and also a lot stubborn... or something like that." He has/would have "a gentle smile not just for business, but because he is a gentle person himself." This prediction happens to reflect his personality which became forefront after he answered the tentacles.
When first introduced, Korosensei was a jovial individual who demanded absurd and seemingly mundane requests despite claiming he would be the cause of the planet's destruction in a year. He was also rather kind to others in general and could switch from silly and childish to serious on the fly. According to Nagisa, Korosensei also was unintentionally petty at others at times and loved gossip, both traits heavily noted through the series.
From time to time pieces of his old personality as The Reaper were visible such as when Terasaka tried to sacrifice Nagisa to kill Korosensei and Korosensei menacingly threatened all of their families if they tried another self-harming attempt like that. In that moment he resorted to his old method of teaching through fear. As the series progresses his character development renders him more and more capable of true empathy and learning to use that empathy to teach lessons instead of through fear and reward like he had with his first student.
Korosensei deeply cared for his students' emotional and physical well-being and would lose his temper whenever any of them were put in danger, even by one another. On the annual school trip to Kyoto, a few of his students were assaulted/kidnapped by a gang of high schoolers hidden in an alley. After searching the entire area painstakingly, he infiltrated the abandoned building where two kidnapped students were being held at and single-handedly beat up all of the high schoolers and scaring them away.
One of Korosensei's attributes was the fact that he was able to connect to each student individually, being an objective, empathic, and observant person who will do almost anything to help his students. This was the reason why all the students respect him despite the fact that he was going to blow up the Earth in a year. Taking care of each student's needs, Korosensei would sometimes be piqued by a student's current problems or interests and would try his best to guide the student along or solve it for them.
Korosensei loved sweets almost to extreme cases, and was also shown to be a very perverted character, a trait he shares with his student Okajima. This characteristic was revealed to be the side effect of the experimentation which made him unable to hide his true feelings.
Main Skills and Equipment
Antimatter Physiology: Due to the human experiments of producing antimatter in a living body by Shiro, Korosensei's entire appearance is an octopus-like creature with multiple tendrils that are his tentacles. Anything aside Anti-Sensei Weapons will be immune to him. It is initially believed that he will self-destruct by the time of Class E's graduation; however it has since been proven that the chances are minuscule at best,
- Protective Coloring: Korosensei can change any color for his skin and it is used for his disguises and camouflages. It is also the principle of the faces which represents his moods. Since it is only apply on his skin, to fully use the ability Korosensei must be fully naked. Although when he is blushing, the coloring won't cover the blushes on his face.
- Mucus: The standard trait of an Antimatter organism, the mucus that Korosensei has varied uses for support purposes, such as waterproofing, cleansing, adhesive and the replacement of tears.
- Liquefaction: After he drank the 4th poison made by Manami Okuda, Korosensei developed an ability to control his fluidity. He can morph into a mass of mercury-like slime. In cost of his massive body and tentacles, Korosensei can fit through any space while retaining most of his abilities. It is unknown that if there are any demerits to over use this ability.
- Absolute Defense: Another trump card never used until the Okinawa trip, Korosensei can shrink his body into a sphere and the remaining energy from the transformation hardens as a crystallized second layer over his spherical body, making him impervious to harm. After twenty four hours, the external shell liquefies and he will slowly absorb energy over a period of time until he fully regenerates. The only drawback to this in the span of a day, he is rendered immobile and is susceptible to being carried around. The only mechanism might be able to breakthrough this sphere is Lance of the Heavens.
- Energy Laser: An ability developed from the Absolute Defense. Korosensei can tap a portion of his inner energy to his tentacles in order to create a laser blast from it. It is capable to annihilate the Anti-Sensei Cloth and blast off anything else with scratches barely left over.
- Molting: A once-a-month occurrence, Korosensei can shed his old skin and use it as a protective membrane either on himself or another individual, protecting them from being hurt even from military-grade explosives. Afterwards, his reaction speed may slow temporarily but he is still fast enough to dodge the assassins of 3-E.
- Regeneration: If one or more of his tentacles are maimed, Korosensei can regenerate the severed limb like a lizard regenerating its tail. However, this leaves his stamina weakened as his reaction speed is dampened, albeit not enough to topple the teacher.
- Surgery Skills: After he was unable to save Aguri from fatal wounds, he start learn about medical operation and surgery methods which he first apply it on Azusa to remove her brain tumor without damaging her. Later, he use it to heal and revive Akari (Kayano) from fatal wounds that was caused by God of Death and Yanagisawa after surgery has been completed. Like his Regeneration and Molting, the surgery also can weaken his stamina, which sometimes need to replenish is stamina during the process of the surgery.
- Superhuman Speed: Korosensei can travel up to the speed of Mach 20. His normally soft and jelly-like head hardens under immense pressure as a process known as the dilatancy phenomenon, which presumably lowers his wind resistance, allowing him to reach inhuman speeds. The only known objects to surpass this are space shuttles which is used for space launch which reaches the speed of Mach 23 and other Advanced-Antimatter Organisms.
- Superhuman Reflexes: Korosensei can react and dodge multiple fires of Anti-Sensei bullets and move away from any harm. His reflexes also allow him to react fast enough to catch or deflect any flying projectile in mid-air using what he has on hand such as handkerchief or even a chalk. Another example of this is when facing off against Asano Gakuho, he was able to open a test book, solve a denoted question on a small slip of paper and close the book without the explosive contained in the book detonating. Plus, he is also fast enough to molt and toss his protection skin over the principal when a normal grenade detonated point-blank in his face.
- Speed Replication: Korosensei's amazing speed allows him to seemingly copy himself dozens of times using after-imagery. Not only can each individual after-image maintain a task for extended periods of time, but Korosensei's "speed copies" are all capable of taking on widely-different tasks both individually and simultaneously without confusing themselves. This technique was primarily used by Korosensei to teach all of Class 3-E one-on-one when a difficult test approached, allowing Korosensei to work with each student separately to work on their problem subjects.
- Superhuman Senses: Korosensei's sensory perceptions are paramount, and can detect even the most minuscule of changes in temperature, light, sound, and smell. Despite having no visible ears or nose, Korosensei has proven to be able to hear things no normal human can pick up on, as well as detect the most minor of aromas, which aided him greatly in evading the assassination attempts of Class 3-E. Korosensei is especially talented in identifying people by their smell, as well as certain materials (such as explosives and poisons). His eyes are also quite keen, and can keep track of objects going thousands of miles per hour without difficulty, as well as detect the slightest of movements that occur quicker than the blink of an eye.
- Superhuman Digestion: Korosensei can digest anything aside Anti-Sensei weapons His teeth can crush any hard materials. Whether he eats something or it enters his body, he can either molten the food first then eject it, or it will just be digested. Although it is not guaranteed that Korosensei will have no irregulars after what he has eaten, it is usually have no tactical disadvantages if it is not a weakness for him.
Genius Intellect: Even before Korosensei gained his powers, he possesses a gifted mind which allows him to learn and understand complex knowledge in a matter of minutes. With his immense intelligence, he was able to single-handedly teach all the subjects and produce amazing results from the bottom of the barrel class of 3-E. Since gaining his speed, Korosensei has become hypercongnitive, and can process information thousands of times faster than the average human being. His incredible mentality combined with his speed also allows him to multitask on up to dozens of jobs at a time (teaching the entirety of Class 3-E individually and then some), all of which seemingly being done simultaneously.
- Master Assassin: As the original God of Death, Korosensei was considered the world's best assassin prior to being betrayed by his disciple. As a result, Korosensei can combat nearly every assassination utilized by both Class E and professional assassins, showing to be extremely observant and stealthy at planning and execution.
- Eidetic Memory: Korosensei is deduced to have an eidetic memory, as he is able to store all that he has learned and use them to his advantage, which led to him being the strongest assassin in the world prior to his capture. In order to become an educator to class 3E, he has memorized all of the test books in Japan so as to be able to coach his students where their weaknesses lie.
- Class 3-E
- Aguri Yukimura
- Shiro/Kotaro Yanagisawa
- The Reaper
- Gakuho Asano
- Tadaomi Karasuma
- Irina Jelavić
- Pegasus Kouga, Monkey D. Luffy and Ruby Rose