Yamaguchi Kumiko, a new teacher at Shirokin High School, has been assigned to teach a class full of the school's most notorious delinquents. Unbeknownst to her fellow teachers, Yamaguchi is better equipped to deal with her rowdy students than most: as the granddaughter of the head of the Oedo family, she grew up around yakuza gang members and has learned to fend for herself. When one of Yamaguchi's students, Kumai, is accused of stealing a bag of money from the head teacher, she is forced to intervene to keep him from getting expelled. But is he really as innocent as he claims to be?

When the students create posters making fun of her and the head teacher, Yamaguchi learns that they have given her a nickname, "Yankumi", which she unexpectedly embraces. One of the students, Minami, is seeing a new girl. One day, he arrives badly beaten and gets into a fight with another student, Sawada. It turns out that the girl Minami is seeing was also going out with a boy from another school, who calls him out on the matter. Inspired by her grandfather's yakuza values, Yamaguchi encourages the boys to stick up for their friend.

A serial purse-snatcher is targeting women in the neighborhood near Shirokin High School, and Uchiyama, one of the students in Class 3-D, is a prime suspect. Determined to prove Uchiyama's innocence, Yankumi and a few of her students set out to catch the real thief.

Yamaguchi's fellow teacher Shizuka, who teaches English, is also working nights at a club in the Ginza district. One of Shizuka's students, Noda, who has developed a crush on her, gives her a necklace, and later follows her to the club, where he sees her throw away his gift. The enraged Noda posts pictures online, exposing Shizuka's second job to the principal, who threatens to fire her. After a talking-to from Yamaguchi, the principal promises not to fire Shizuka if all of the 3-D students can earn at least 30 points on their English midterms. Yamaguchi gets to work preparing after-school study sessions for the students, but will it be enough to save Shizuka's job?

Sawada finds Yankumi's lost phone and sets out to return it. In doing so, he ends up in a house filled with Yakuza and learns the truth about Yankumi's family from her grandfather. Meanwhile, the teachers are on the lookout for a violent gang of young men who have been attacking pedestrians, and Kumai has become smitten with a girl from another school, who he learns already has a boyfriend. Later that day, Kumai learns that the girl's boyfriend is the gang's next target. Concerned for her safety, Kumai rushes after them. While he is watching, the gang members corner the girl and her boyfriend, and the boyfriend runs off. What will Kumai do?

It's time for Shirokin High School's annual sports tournament, and the initially reluctant students of class 3-D have been goaded into participation by dismissive remarks from the head teacher, but they need one more student to field a basketball team. Incidentally, Yankumi has discovered that there's another student in the class, Yuki, who never shows up and she never even knew existed. But Yuki, who left because of bullying by Minami and Kumai, shows no interest in going back to school. Can he be convinced to return and face his fears?

Yankumi is struggling through parent-teacher conferences, but when it's time for Sawada's meeting, his parents don't show up. Later, he receives a visit from a girl who turns out to be his sister. Through these incidents, we learn that Sawada lives alone due to a falling-out with his parents. When his sister takes an unnecessary risk, Sawada steps in to save her, but ends up shouldering the blame and getting arrested. The next day, the head teacher announces his expulsion. Can Yankumi and the boys of class 3-D do anything to help?

Because of Shin's scary story, Yankumi is scared to walk alone to the school hallway. One time she left her phone and thinks that someone was following her only to find out that it was a little boy. The boy was Yuta Nakashima-sensei's step son. The boy think of the Nakashima as her mom but since they aren't blood related, Nakashima thinks they are not. How will Yankumi give Nakashima her senses?

Yankumi is happy for class 3-D will be hosting a volleyball tournament however they will not the playing.Yankumi thought of something to make them participate and thought of forming a cheer-leading group who will yell chants. Class 3-D aren't into it at all so she told them that they'll be meeting girls there. Everyone agreed and made there efforts. But something is messing everything up. Will things go smoothly?

Everyone is lovelorn that day. 3-D went to a group date wearing formal clothes to keep the fact that they are from Shirokin but soon was revealed. Yankumi saw her long time crush with a girl, and Tetsu the guy who has a crush on Yankumi forever felt that she'll never get Yankumi. But that wasn't the problem, one night, a boy fleeing from a video store he shoplifted from was bumped by the 3-D and were accused of steeling. How can Yankumi prevent them from being expelled?

As usual, Yankumi was called for her students got involved with cops but this time in a positive way. The 3-D became heroes and for some reason, Yankumi gave so much attention of herself although she didn't participate in the hero thingy. Meanwhile, a proud father was giving so much attention to his son which made him mad and say hurtful words . The father passed away all of a sudden. The boy felt bad and put himself in trouble. On the other hand, while Yankumi is trying to help him, some curious reporters found about her deepest darkest secret...

FInally the magazine stating Yankumi's back ground came out and made a lot of commotions. Yankumi was forced to resign but she doesn't want to. The students on the other hand were so mad about the bad article and were force to meet the press but instead of clearing things up, they made it worst for they beat the press. Now the Shirokin High has a reason to expel them and the only way for them to graduate is if Yankumi will resign. What will they do? Owe

In the first episode, two characters are introduced. Hayato and Odagiri. Hayato is the leader of class and childhood friend of Odagiri. For some reason, Hayato and Odagiri fought and now Odagiri Ryu quit school and is now working to some dangerous guy. Odagiri refuses to go to school as well. How will Yankumi bring back her precious student back to school?

Yankumi has convinced Ryu to go back to school but Hayato is still against him. The atmosphere in class suddenly changed when the two met. Although Ryu isn't against the reconciliation thing, Hayato still holds grudge of what Ryu did in the past. While Yankumi tries her best to let the two make up, Hayato took Yankumi as an annyoing teacher leading him to challenge her.

Some guys are around the neighborhood beating people up and claiming that if they have any problem, they can go to Kurogin high. They also say that they are Hayato and Odagiri. One night the two were set up on a crime they didn't commit and the worst is no one believes them and the police officer wants them arrested. How will Yankumi find the impersonator and clear her students name?

Girls are coming to Kurogin high and class 3-D are so excited but ended up scaring them. On the other hand, Tyuchi, another student met one of the girls in a books store shoplifting. Tyuchi didn't turn her in and brought her to an arcade instead. He then knew that the girl is the teachers pet who is considered "PERFECT STUDENT" of her previous teacher whom he didn't get along with. While in the arcade, the teacher caught them and got themselves in a serious trouble.

It's valentines day and Takeda is having a huge crush on a girl working at a restaurant as a waitress. Takeda never said anything to her but alwys eats in the restaurant just to see her. He does everything to be noticed even accepting a "make believe" from her friends which made the girl totally hate him. Takeda felt really bad while Yankumi gave him good advice. But when he knew that the girls boyfriend is two timing her, it's up to him on how to make things right.

In this episode the story focuss on Hyuga. When they were asked if they already knew what to do in the future, Hyuga had set his mind into something and actually, he had his mind into it now. Hyuga started working to a guy but made his mother really worried. On the other hand, Hayato and Odagiri found a wallet and returned it to the owner. The two ended up taking the guy home and discovering something.

Yankumi is on a job hunt for after three months she's out of the school considering that the chairman hates her. On the other hand, her student will soon be so Yankumi tries her best to find a job for them. Tyuchi was the first but because of a street fight, he lost his chance of applying. Yankumi was disapointed but still tried her best to find jobs for them and made the students promise not to fight until graduation.

Kuma's shop (previous student form season 1) is being threatened by some bad guys but refused to tell Yankumi but did seek help from Hayato. He figured out that since he graduated, he is no longer a student of Yankumi so he can't just ran to her every time things gets bad for him. On the other hand, the family of Hayato will be introduced and where in the world did he get his jerky attitude.

The story line in this episode is Odagiri and his father. The father of Odagiri is a high ranked police which is the opposite of Yankumis grandfather. The father is against the friends of Odagiri and locked him up but his friends helped him break out. How will Yankumi helped her student when her family is in the line?

After few days, the class 3-D will be graduating but problems occurred when Kudou came. The class 3-D promised not to fight till graduation but when Kudou's gang attacked them... On the other hand, the chairman is determined to kick out Yankumi together with her 3-D. What will Yankumi do?...

Three years after her resignation from Kurogin Academy, Yankumi returns as the new homeroom teacher of Akadou Academy's 3-D! Upon her arrival, she discovers that the class is full of delinquents, and is divided into two opposing groups that are always at each other's throats. One of the students, Kazama Ren, is suspected to be behind a series of muggings, and while the rest of the class doesn’t seem to care about his predicament, Yankumi resolves to prove Kazama's innocence.

Determined to teach class 3-D the true meaning of comradeship, Yankumi seeks out different ways to relate and get closer to the students, yet all her efforts seem to be thwarted. Meanwhile, the two heads of said groups, Ogata Yamato and Kazama Ren, decide to have a one-on-one fight to finally determine who's the better boss, but when this turns out futile, they find themselves settling their differences in the most unusual of means.

The Spring Inter-Class Competition is nearing, and now that Ogata's and Kazama's sides have already made peace, Yankumi is more fired-up to have the whole class join and conquer the rugby match. Ichimura "Ichi" Rikiya, Yankumi's student, meets an old classmate from junior high, Takasugi, who seems to be a quiet, studious boy, but actually has a dangerous side to him.

Yankumi, the teachers and class 3-D meet Kaoruko, Kazama's older sister. She visits Akadou Academy, and chastises Kazama upon finding out that he has a part-time job, which is prohibited in school. Amidst the "Springtime Eliminate Delinquency Campaign" organized by Sawatari, Kazama faces the possibility of expulsion for deliberately hitting a police officer, causing him to have a falling out with his sister.

Yankumi talks to her students’ parents about their future during PTC, one of them being Honjo Kengo's dad, a tofu store owner. When he collapses from over-fatigue, class 3-D fears that Honjo will have to drop out, so they decide to raise money to help him out by trying out different jobs. Honjo, on the other hand, encounters an old senpai of his, Narita, who lends him the money he needs – but with serious consequences.

Class 3-D is planning a hook-up party with some girls from the neighboring schools, but Kuraki "Kura" Satoru is indifferent... for he is actually in love with Saki, a sickly girl he met a week prior. Wanting to take a break from the confines of the hospital, she calls Kuraki, and the two go out to have fun, until Saki's disease kicks in. This enrages her parents, and they file a complaint to Sawatari, prohibiting Kuraki from ever seeing Saki again. Unable to bear her student's misery, Yankumi steps in to help.

It's time for Akadou Academy's annual festival, and Yankumi encourages class 3-D to participate. At first, everyone is uncaring, but the promise of girls visiting the school during the event ignites their enthusiasm, and they agree to form a coffee shop named "Hottie Café". Trouble arises, however, when Ogata, Kazama and the others unwittingly piss off Goda Ryuuji, an Akadou alumnus with a notorious reputation, who retaliates by vandalizing the school the night before the festival.

Ami, Kuma's wife, is approaching her due date. While an excited Yankumi prepares for the baby's birth, one of her students, Kamiya Shunsuke, finds himself frustrated when he gets beaten up by an Ara High bully in front of his girlfriend. Subsequent events with his mother and Kuma take a toll on his temper, and Yankumi races to rescue Kamiya when he picks another fight with a bunch of punks, as well as teach him an important lesson about strength.

Class 3-D is awarded for catching a thief during a secret night visit to school, yet their celebration is short-lived when they get into a scuffle with a few classmates who gets themselves involved with a bad crowd. With only a few months left before graduation, Yankumi strives to reunite everyone and restore 3-D's friendship.

Curious about why Yankumi is so strong despite her looks, Ogata and Kazama's group decides to follow her home, and gets the shock of their lives when they discover who she really is. The cheery atmosphere in their family greatly contrasts Ogata's – his father, a strict teacher from the elite Kaitoku School, is very disappointed with Ogata's status as an Akadou delinquent, and blames his irresponsibility for his parent's divorce!

It's almost time for the finals, and class 3-D is determined not to fail in order to have a great summer break. Apart from that, they also have to avoid expulsion by not getting into any more trouble, but that appears unlikely when Goda is on the loose again. Swearing vengeance, he raids Akadou Academy and gravely injures Kazama, leading to immense chaos that seems impossible to stop, even for Yankumi herself.