Sae Chabashira

Sae Chabashira is a Japanese history teacher and the homeroom teacher of class 1-D.

Background
Some time ago, Sae attended Advanced Nurturing High School and was a student in D-Class. She went to school with Chie Hoshinomiya who mutually see each other as a friend. It is unknown what she did after graduating but according to herself, she lived a life full of regrets before becoming a teacher at her old high school.

Appearance
Sae Chabashira is a young adult woman with a well-endowed voluptuous body and long brown hair that is tied in a ponytail with brown eyes. She is mostly seen with a serious expression on her face though it does change into a smile on occasion.

Personality
As a teacher, she is very serious about her job as she makes sure to teach the class about their subject. She follows the school rules to the letter as shown when she bluntly told Ken Sudō he would be expelled from the school for failing the test.

She appears to have a sadistic side as she called her students disappointing as she informed the students that they wouldn't receive points after they blew through them in a month and took joy in their anguish. She also demanded a large sum of points from Kiyotaka to stop Sudō from being expelled, she did this because she knew that he didn't have the amount to pay for such a thing.

Despite that, she shows some leniency in teaching the class as while she was teaching the students were either sleeping or playing their phones. She was also willing to rescind Sudō's expulsion after Kiyotaka and Suzune paid her to halt their classmates' fate.

She seems to have taken an interest in Suzune and Kiyotaka as their selfless deed was something she had never seen at the school. She appears to recognizes the depths of Kiyotaka's intelligence and figure out that he was hiding his talents on purpose as he wouldn't be in the lowest ranking class if he was that amazing. She tried blackmailing him to reach Class A after his father requested he be expelled but he refused to comply.

She is shown to approach most things in complete indifference as shown when she was not fazed by Kiyotaka grabbing her by the collar after she ordered him to reach for Class 1-A, not even making a threat. She was also amused by Kiyotaka's refusal to comply with her and his father's wishes to advance even though she previously threaten to expel him. According to herself, she has a life of regrets meaning there were some terrible events that transpired some time ago.

She has been seen smoking a cigarette when by herself.

Plot
Sae introduced her to the students of D-Class and told them she would be their teacher for the next three years. She told them the importance of points and how they could use it, much to their joy. For the next month, she teaches while her class goes through their points or text in class barely paying her any mind.

After the month is over, she called her students disappointing as she informed the students that they wouldn't receive points after they blew through them in a month and took joy in their anguish.

Later on, a quiz is given and she informed them should any of them fail they would be expelled for it. After the test, Sae announced to the class most of them did well but only Ken Sudō would be expelled as he was one point away. She told the shocked boy that he would be expelled when the day is over as she leaves the classroom.

Sae went out to the roof to smoke where she was met by Kiyotaka who she told to go to class as he decided to talk with her. He asked her about equality and she seemed intrigued by someone so young asking her. After she gave her answer, he requested that she halt Ken's expulsion and offered her points to give him a higher school since he learned it was within the rules. As she mused at his offer, she states she would have accepted if he gave her a large number of points but he couldn't give her it. However, Suzune stepped in and offered points as well as Sae was amused by this and accepted their payment and tells them not to tell Ken he won't be expelled. Sae left and told them not to disappoint her since they could possibly advance to A-Class, which is something nobody in the history of Class D had done. Suzune informed her that she intends to ascend to Class A stating those with defects can overcome them and advance as Sae leaves amused by this.

Following Sudō's fight with Class C, she went to his hearing where she impressed with the Student Council President residing over it. Manabu told her that his busy schedule permitted his presence over the meeting as Sae is amused by his reply. She smiled while watching as Kiyotaka snapped Suzune back to her senses after she got scared by her brother's appearance at the hearing. Sae then watches as Suzune eloquently argues with C-Class and even makes them mess up how the situation was caused before bringing out Airi Sakura who witnessed the incident even bringing photos of it. When Kazuma Sakagami notes on how it simply proves Airi was there the photos don't tell who started it, he talks with Sae for a comprise as she appears intrigued. Sakagami states a week suspension for his students and a two week for Ken but Sae doesn't give an answer as Suzune argues with C-Class for all accusations being dropped against Ken. Manabu then broke up the quarrel by telling everyone he would make his decision on the next day.

After C-Class withdrew the complaint, Sae summoned Suzune to the school roof where she inquired as to how Suzune had gotten the other class to withdraw their statement but was given no answer. Instead, Sae told her to understand Ayanokōji better as she needed to know the "defective" traits of those around her and that he was the most defective since he hides his amazing talents.

Sometime during the school cruise, Sae was contacted by Kiyotaka's father who told her to expel his son. With this, she gets in touch with Kiyotaka and he meets her while a play is going on as he questions her reasons for summoning him. Sae doesn't tell him his father contacted her but does inform him that a mysterious man told her to expel him immediately. Kiyotaka is indifferent to this and tells her that he has done nothing to get himself expelled as Sae tells him regardless of his intentions it's her judgment. She then offers him a deal if he started making effort to reach A-Class, she'll protect him but he refuses and she states he will be expelled. In response. he grabs her by the collar stating he will not be manipulated and she'll regret her attempts to do so. Unfazed by this but amused, she states her life is filled with enough regrets and tells him to make his decision.

When the ship reached a Deserted Island, Sae explained to the students that they will undergo a survival test for the next week and they will get bonus points should their class succeed.

On the final day of the test, she was at the stands when Kiyotaka appeared carrying an unconscious and battered Suzune who was ill. He asked for her to withdraw as Sae questions what he intends to do as he requests that he become the leader of his class since it was within the rules.

After the survival test, she summoned Kiyotaka to the theatre where she commends him on his victory over the other classes as he shrugged it off. He then asks if someone really wanted him expelled and he states he won't do anything for her without proof. Sae simply revealed her knowledge of his past as the evidence before she compared him to Icarus and finally tells him that it was his father who made the request to expel him. She states his father replied to his refusal that one day he will pick expulsion of his own free choice. Once again, Kiyotaka refused her offer to go to Class A, to which Sae doesn't protest or threaten him. Sae then asked him what he plans to do now to which he vaguely answers as she smiles in amusement.

Trivia

 * She is a former student of D-Class.