Kaede Kayano

Kaede Kayano (real name Akari Yukimura) is a student in Class 3-E of Kunugigaoka Junior High School, taught by Korosensei.

Appearance
Kayano is a girl with a short stature. She has a lithe frame, hazel eyes, and green hair which is always fashioned in unique, cat ear-styled pigtails.

It was later revealed that her green hair is originally black and her hair is actually long and wavy. Her hazel eyes also became red due to her blood lust.

Personality
Kayano is one of the more passive members of the class. She frequently acts as support in assassination attempts with her ability to assess the situation and herself. She experiences a severe complex when it comes to sex appeal, usually loudly voicing her discomfort when being around large breasted women. Despite her apparent passive nature, she's a kind and cheerful person who's also very strong willed and extremely devoted to things that interest her.

In Chapter 129, her kind and cheerful personality shown during the school year is revealed to be fake to protect her true identity and motives. Her only true attribute was her tenacity and her sex appeal complex, the rest being a mere fabrication.

History
Kayano's past is finally revealed in Chapter 129 and Chapter 130. She is revealed to be Akari Yukimura, the younger sister of the late Aguri Yukimura who prior to joining Kunugigaoka, she was a famed prodigal actress who went by the stage name of Haruna Mase. At some point during her career, her manager suggested that she take some time off which she did. Eventually, people stopped recognizing her all together and she continued her time as a regular middle school student.

One day, Akari was wandering outside the research facility her sister helped out at and witnessed an explosion take place. Because of her small stature, she was able to navigate her way through the rubble to get to Aguri. When she finally reached her sister she saw her bleeding with a tentacle creature that would later become Korosensei leaning over her body. The creature sped off soon after leaving a note addressed to Aguri's relative telling them where to find him. Akari hurried to her now dead sister and while mourning for her, she came across the tentacle cell liquid.

She took her sister's research and home and began researching the tentacles and what they were for and began planning her revenge as well as her ultimate act. She even transferred to Kunugigaoka under the fake alias of Kaede Kayano, which was the name of a one-shot character she once played, and got herself put into Class E by destroying some of Chairman Asano's valuable possessions. Soon after, she injected herself with the cells and dyed her black hair green.

At some point not long after, she met Nagisa and decided that he was the perfect candidate to conceal her and place her as one of the background characters. She commented on his long hair and styled them into his signature pigtails. She introduced herself to him and thus their "friendship" began.

Plot
At the first chapter, Kayano was the one who asked the target teacher what name they should refer him as; he tells her that they can decide. After Terasaka's failed assassination attempt, she says the name she thought of for the teacher: Korosensei. In spite of her main character status, she tends to remain on the background, being geared mainly towards logistical support.

She gets the spotlight in Chapter 80, in which she devised an assassination attempt purely based on her love of pudding. Although the attempt was unsuccessful, her classmates were impressed on how straightforward and well thought out the plan was.

During the following arcs, she remains occupied on logistical and supportive roles, being Team A's only non combat member during the God of Death incident, and helping the class during the School Festival and the Play.

In Chapter 128, she returns to the spotlight. Along with Nagisa, she's tasked with storing away the props from the play Class E had recently made, with Korosensei quickly offering to help them. In the shack, after reminiscing her time spent with the class, she reveals she possesses two black tentacles sprouting from the nape of her neck. She suddenly attacks Korosensei, stunning him. She promptly states her love for him, along with her desire to kill him.

In Chapter 129, she attempts to kill Koroensei with a pitfall trap, filled with anti-sensei material at the bottom of it, forcing him down with her tentacles. Her attempt is thwarted once he uses his energy beam to blow up a part of the wall to escape, Kayano being unable to stop him after instinctively recoiling in defense. The sound from the explosion alerts the class, who arrive and are shocked at the revelation of Kayano having tentacles (Itona in particular). She informs Korosensei of her current name being fake, and gives him an obvious hint of her true identity and connection to him. After promising to kill him tomorrow, she exits the school ground, completely indifferent to her classmates and their reactions.

Nagisa Shiota
Kaede and Nagisa are regularly seen together and appear to be good friends. During the Assassination Test of Courage, Korosensei paired Nagisa with Kaede. In Chapter 128, it's revealed that her reason for being around Nagisa is to merely disguise her massive bloodlust. This is confirmed in Chapter 130 however in Chapter 133, it was revealed that as she continued on throughout the school year, she developed genuine concern for him. It's also revealed that she gave him his current hairstyle, albeit with the intention of making him stand out more so she could blend into the background with ease. It has been implied that Kaede may have developed some degree of feelings for him during the year and according to the official character book, she was upset when Bitch-sensei kissed him.

Karma Akabane
Oddly enough, she was unaware of Karma's reputation for violence when he joined Class E, and thus was slightly wary of him at first. However as time went on they are shown to have a friendly relationship, as they are seen together regularly. The reason for Kaede's unawareness of his violent fame was because she joined the school directly as a third year.

Korosensei
Korosensei is her target. Like most of the Class E students, she quickly warmed up to him. She was the one who gave him his current name, something he was truly grateful for. In Chapter 80, it was revealed they share the same passion for sweets, prompting her to devise her own assassination attempt, which was based completely on their mutual interest in pudding. In Chapter 128, she stated that she loved him, however this could've most likely been the influence of the tentacles or meant to throw him off. She accuses him of causing the death of her older sister and since obtaining tentacles, she considers him her nemesis. In Chapter 133, it was revealed that her initial will to kill him gradually dropped as she got to know him and she began thinking that there might be more to his side of the story than she knew.

Abilities
Perseverance: By far her greatest talent. She's shown to be able to withstand the hellish pain from the tentacles, without any kind of treatment, for over a year. The average person wouldn't be able to function normally, and would expire out of pure pain in three days without help. In spite of that, she keeps a completely normal front, and is able to go through her entire school year without showing any kind of discomfort.

Assassination: Although hidden during most of the manga, she clearly excels in the skills required for a talented assassin, being able to blend into the background very easily, keeping her true objectives and intentions hidden from friends and foes alike, regardless of their skill at discernment, and being able to strike without being noticed. Shiro states that, out of all of the Class E students, she's the most qualified one to be an assassin.

Acting: As a professional and prodigal actress, she's renowned for her skill to play any kind of role flawlessly. Due to this, she was able to fool Class E's students and staff during the school year. All of them believed the fake identity she created.

Intelligence: She's revealed to have a very high level of intelligence, as she was noted for being the first one to pass the Kunugigaoa transfer student exam on her first try. She was able to implant the tentacle cells into herself, and learning to control them in a very short time. Unlike Itona, and despite not receiving any kind of treatment, her intellect isn't impaired in the slightest by the tentacles.

Quotes

 * (To Nagisa Shiota) "The school trip was fun, we got to see different sides of everyone."
 * (To Karma Akabane) "Once I decide something, I move straight towards it. That's how I am."
 * (To Korosensei) "I love you, Korosensei. Now die."
 * (About Nagisa Shiota) "There were times where I was worried about him, but he was always by my side all while setting aside an earnest bloodlust."
 * (To Korosensei) "I'm the younger sister of Aguri Yukimura. Get it yet, murderer?."
 * (To Class E) "At first... my bloodlust was pure. But the more time I spent with Korosensei, the more I started to lose confidence in it. Like, 'What if there's another story behind his actions that I don't know about?' and 'Should I make sure I'm right before I kill him?' And at that time, the bloodlust in my tentacles started to swell up. They wouldn't let me give up the assassination."

Trivia

 * She was called "Forever 0" during class 3-E training using code names.
 * Her favorite food is pudding, and she is shown to have an extensive knowledge about it.
 * She is the one who gave Korosensei his current name, which he has used ever since.
 * Her hobby is karaoke-scoring.
 * Her inability to swim, her fixation on breasts, and her love of sweets, are traits she shares with Korosensei and to a lesser extent, Itona, though she had her breast fixation even before the implantation. Her strong will, almost bordering on obsession, and drive once she decides to do something, however, is another key trait they share.
 * Her best subject is Japanese, while her worst is P.E.
 * She dislikes people that are big-breasted, except Tōka Yada.
 * Her dream is "to be become a capable woman."
 * When the tentacles asked her what she wanted, she answered, "To be a killer."
 * In the "Girls you're interested in" ranking made by the boys on Chapter 19, she was ranked 4th, with style listed as her best point.
 * She can't swim.
 * In the art rankings of Volume 5, she was placed 3rd among the female students.
 * She is the shortest student in class E.
 * In the popularity poll of Volume 12, she was the lowest ranked of the main trio, at 9th place.
 * In the tankobon extras, her statistics were listed as:
 * Physical strength: 2
 * Mobility: 2
 * Close-range assassination: 2
 * Long-range assassination: 3.5
 * Academic ability: 3
 * Characteristic skill: 4 (Sweets chef)