Episode 37

Confession Time is the thirty-seventh episode of the Assassination Classroom anime and the fifteenth episode of Season 2. It premiered in Japan on April 22, 2016.

Summary
The battle between Kayano and Korosensei concludes with Nagisa using Irina's kissing technique on his friend and Korosensei removing her tentacles. As promised, Korosensei begins to tell his story of how he was the original God of Death, and meeting Aguri Yukimura while in captivity by Shiro.

Plot
Kayano continues her ferocious attacks on Korosensei. It is immediately obvious to the class that the tentacles are consuming her mind and Itona predicts that if nothing is done to prevent it she will truly die regardless of whether Korosensei is killed. At that moment images of Korosensei’s face sprout in front of the class, whilst still defending himself. He states that the only way to save Kayano’s life is to take away her tentacles but unlike Itona’s case, they do not have the time to calm her bloodlust, hence he will need to remove them during their fight. It falls on the students to come up with a way to subdue Kayano for just a brief moment, when Korosensei will intentionally expose his main weak point where Kayano will let down her guard. Kayano’s next attack forces Korosensei to return his attention back at her, as the students suggest various ways  to do as they were asked. Nagisa thinks back to all the lessons they learned throughout the year. While most options are either ineffective or will result in Kayano being hurt, he suddenly remembers one particular technique.

Back to the fight, Korosensei exposes his crescent moon tie. Kayano takes the bait and strikes at his heart. His blood spitting out of his mouth makes Kayano believe that she has succeeded. However her opponent catches her off-guard and wraps his tentacle arms around her body. After pulling her towards him Korosensei tells her that he had promised her sister to not let any students fall. At that point Nagisa approaches the struggling pair. Not believing that everything Kayano had done with the class the past year was all an act, he calmly walks up to her and kisses her in the mouth. As the stunned class watches on, Kayano is brought back to her senses but is knocked out in 15 hits. Korosensei then surgically removes the tentacles from her neck.

With the battle over, the students crowd around Kayano. Rio Nakamura and Karma Akabane tease Nagisa about the kiss while Irina critiques that he still has much to improve on. Korosensei starts to recover from being hit in the heart but is still able to dodge an anti-sensei BB shot. The culprit is a hooded individual accompanied by Shiro. He is disappointed that for all of Kayano’s talk about revenge, she still is not capable of killing her target. Lamenting that all of the assassins had been defeated, he and his accomplice are the last ones left. With that, Shiro removes his mask (which was a device that altered his voice) and Korosensei recognizes the face to be Yanagisawa. Yanagisawa promises to kill him by March, and the pair leave the scene. Afterwards, Kayano wakes up. She tells the class that at first revenge was fueled by her pure bloodlust. But as she got to spend time with the class and Korosensei throughout the year, the more she began to think there was more to the circumstances that led by her sister being killed. Her weakening resolve however was not agreeable to her tentacles, and her bloodlust begun to be uncontrollable; hence why she carried out her original plan. Nagisa comforts Kayano; stating that because of her he became comfortable with his long hair, and that everyone agreed to her suggestion to name their teacher “Korosensei”. Furthermore, the smiling warm girl they knew has long been accepted as their friend. Kayano weeps at this, glad that she no longer needs to put on the charade anymore.

Isogai once again requests that Korosensei tell the truth about himself. He starts off with what Karasuma and Irina had discussed at the summer vacation – the broader the knowledge of an assassin, the better you will be able to teach. He puts this forward to the class and asks them why he is such an effective teacher despite this being his first year being so. Korosensei confirms that until two years ago, he was known as the God of Death. Furthermore he reveals that either he dies at the hands of somebody, or his body will explode and take Earth along with him by March.

Korosensei then begins retelling his life. As a human boy growing up in a war-torn region, the only thing he learned was dying. To that, he decided to become an assassin. He honed his skills to kill people from intellectuals to powerful figures. In ten years he earned the moniker of the God of Death. He is later taken captive, and became a guinea pig to be tested on by the researcher Yanagisawa. The God of Death soon became acquainted with a female lab worker named Aguri Yukimura. The assassin thought she could be of use to him but is somewhat bothered by her fashion sense. He decided to bide his time, and will covertly control the experiment so that he can use his new power to escape one day. He also witnessed Yanagisawa’s cruelty to his fiancée.

In the next three months, the assassin and Yukimura became close, and she reveals that she is a teacher at a school. In fact, she was somewhat awed that a professional assassin was schooling a high school teacher about quadratic equations. The assassin recounted how he was betrayed by his apprentice and could not understand where he made his mistake. Yukimura believes that his pupil wanted to be seen by him, something the assassin initially did not understand. More time has passed, and the two grew more closer, though Yanagisawa sees Yukimura as nothing more than a pawn. One day Yukimura asks the assassin about the exam questions she has prepared, and the latter finally understands her meaning about wanting to be ‘seen’. Happy at this, he starts to help her out. At this time, it was the beginning of the school year for the current Class 3-E, two weeks out from the moon becoming its permanent crescent-shaped layout.

Differences between Anime and Manga

 * In the manga Korosensei as a human was seen attempting multiple times to escape with different methods, a couple of examples being manipulating some of the scientists or biting Yanagisawa. This does not happen in the anime.
 * The previous batch on Class E in the manga was never shown in the anime, which skipped directly to the current generation.
 * The anime does not show ending a civil war as part of Korosensei's accomplishments.
 * Kayano start to regain her sight when Nagisa's kiss reaches 5 hits instead of 6.
 * Korosensei's capture scene in the anime was forwarded to when he told Aguri after he briefly teaches about quadratic equations while in the manga it happens on his first day in the research lab.
 * Shiro's profile and position was never mentioned in the anime.

Trivia

 * This is the first episode to feature new opening and ending themes.
 * The title has also changed from "Assassination Classroom Second Season" to "Assassination Classroom Final Season".
 * Korosensei narrates the second half of the episode instead of Nagisa.