Kazumi Kanda begins sixth grade full of hope, but her new homeroom teacher, Maya Akutsu, quickly turns things into a nightmare. Akutsu suddenly gives the class a test and announces that the two students with the lowest scores will be responsible for all classroom chores.

After Hikaru defends Kazumi, Akutsu forces Hikaru to take Kazumi’s place as a chore member. Kazumi asks Akutsu to forgive Hikaru, but Akutsu refuses and says she will only speak to the two students with the highest grades. Yusuke is dealing with problems of his own, while concerned mothers approach Maya.

For the school’s anniversary celebration, the class is preparing a dance. Akutsu tells Hisako, who struggles with rhythm, that she does not have to participate and threatens punishment for students who perform poorly. Outraged, Kazumi tries to protect the others and suggests that the class boycott the event.

After the students’ attempt to boycott the dance, Akutsu tightens her control and divides the class into groups. Kazumi’s group struggles from the start, and another problem arises when Mari’s purse is stolen.

Kazumi is accused of stealing Mari’s wallet and becomes bullied and isolated by her classmates after refusing to reveal who actually took it. Her isolation worsens as her good friend Yusuke continues to be absent from school for an unknown reason.

Akutsu declares that there will effectively be no summer vacation and that she will continue teaching during the break, rewarding good grades. Most of the class is too afraid to disobey and agrees to attend, but Kazumi resists and tries to remind everyone what is important.

Kazumi and three others decide to enjoy their vacation instead of following Akutsu’s demands. When the new term begins, they discover that their desks have been removed from the classroom, and Maya decides to completely ignore them.

As the students prepare for middle school and some study for private-school entrance examinations, Akutsu warns the others not to interfere with the exam candidates and decides to cancel future school events. Hikaru objects to Maya’s emphasis on tests, and a fight breaks out in class 6-3.

As parent-teacher conferences begin, Akutsu gives each student a document containing not only their grades but also information about their behavior, secrets and lies from the previous months. She threatens them with having their parents see the reports unless they do what she says.

As the students unite against Akutsu, the atmosphere in the classroom improves and they establish a cleaning schedule despite her rules. Meanwhile, the school board learns about Akutsu’s classroom methods after a post appears on its website denouncing her educational policies.

Akutsu becomes ill and is hospitalized from overwork, disappearing from the classroom. Namiki unexpectedly discovers the reason for her overwork and changes his opinion of her, while the vice principal wants her dismissed because of the problems surrounding her. The students of class 6-3 make a plan to try to bring Maya back.