Kinpachi gets two transfer students at the start of the second term. Although the other students try to make them feel welcome they make no headway. Kinpachi later discovers that his son Kota has collapsed on his way to school. The doctor diagnoses him with a type of leukemia. Kinpachi, who lost his wife to cancer, is devastated.

Kinpachi's heart is heavy, with two students who just won't fit in, and worry over his son, who has been hospitalized. Nao is called into the Principal's office and reprimanded for her bad attitude. Meanwhile, Masanori seems to be suffering from emotional problems too.

Nobuta has been repeatedly tardy. Kinpachi thinks he's just been oversleeping, but in reality, he has family problems. Seeing how frustrated his son is at not being allowed to leave the hospital, Kinpachi decides to tell his son the truth about his illness.

Kosaku becomes more emotionally unstable when he learns the truth about his illness. Losing his hair due to chemotherapy aggravates his emotional state. Kinpachi does his best to encourage his son, at times with strong words, at times with tender actions.

When Kinpachi takes a cap which another teacher has knitted for Kosaku to the hospital, Kosaku shows him one that a young female cancer patient has given him. For the first time in weeks, Kinpachi sees him smile.

Kosaku uses a computer to find out all he can about his cancer, so he can fight it. Meanwhile, former 3B students gather together in order to put into effect a suggestion made by Kinpachi years ago--to register at a bone marrow bank when they turned 20.

During class, Kinpachi confiscates a note the students have been passing around. He is stunned to find that the students suspect that Naomi is in love with another girl. When he finds out that Naomi once suffered from bullying, he lectures his class on "love."

When the number of case of purse-snatching increases around the school, an anti-crime committee is set up, and former 3B students volunteer to do night patrols. Meanwhile, Kosaku is finally moved out of isolation.

The students are given mock interviews to prepare for high school entrance exams and Kinpachi is amazed by what he hears. Meanwhile, he is concerned about Tadashi, who has been absent from school.

One morning, on his way to school, Tadashi finds Mr. Inui's wife Eiko doubled-over on the road. She is about to have her baby. With the help of people nearby, Tadashi manages to get her to the hospital in time. The kids at school excitedly talk about the baby, but Nao attacks Mitsuhiro for speaking like a girl. Meanwhile, Kosaku is allowed a visit home.

Tadashi's brother Takeshi shows up out of the blue. When Tadashi begins scolding him, his brother starts beating him up. A kerosene stove gets knocked over, starting a fire. Meanwhile, Kosaku takes a turn for the worse.

Kosaku is placed in isolation again, in order to receive treatment to raise his white blood cell count. Kinpachi worries about him, but Kosaku urges him to turn his attention toward his students who are preparing for high school entrance exams.

To the great joy of her classmates, Naomi begins coming to school again. But Miki refuses to take the entrance exam, believing she is responsible for her father's suicide attempt. Meanwhile, Kosaku undergoes aggressive treatment at the hospital.

The results of the entrance exams cause an uproar at school. In the midst of this, Mr. and Mrs. Inui bring their newborn baby to the classroom. As everyone oohs and ahhs over the baby, Miyuki drops a bombshell.

The private school entrance exams are being held today. Yamakoshi and Suga get into an altercation with students from another school. Meanwhile, Nobuta has his father and Kinpachi worried when he doesn't come home one day.

Natsumi and Nami post a message on a "dating" website. They immediately receive a response, and agree to meet the boy, who turns out to be a middle-aged man. Natsumi is later called out alone by the man, who then kidnaps her.

Two of Kinpachi's students happen to read a magazine article about a school teacher named Narusako, who committed murder. They immediately connect him with Masanori, who has the same last name, and begin hounding him for details about his father.

Nao and Mitsuhiro get into a vicious fight over Masanori and his father. Masanori's anger with the magazine that published the shocking article continues to build. Worried about him, Ken goes to his father, a lawyer, for some help.

On an Open House day, Kinpachi has his students do a debate on the subject of the magazine's handling of Masanori's story. Kinpachi is pleased to see how much his students have matured. Nao gets help thanks to Kinpachi and Mr. Honda.

Kinpachi tries to talk Nao into returning to school. He and Ms. Honda plan an exercise in class where the students explore "sexuality" and "the role of men and women in society." Meanwhile, Nobuta decides to go and live with his mother.

Nao has returned to school, and is slowly being accepted as a boy by everyone in the class, except for Mitsuhiro. Kinpachi tries to find out what Mitsuhiro's problem is. Meanwhile, although Kinpachi is overjoyed by his son's release from the hospital, he has a problem of his own. Principal Senda has ordered Kinpachi's transfer to another school and Kinpachi finds himself unable to discuss it with his fellow teachers.

The school year is drawing to a close, and soon it's time for graduation. To the very end, Kinpachi Sensei has words of wisdom for his students. At the graduation ceremony, Nao gives a passionate speech before students, teachers, and parents, thanking them for their understanding and acceptance.