Nozomu Itoshiki, a direct marketing businessman, is chased by a mysterious religious group called Hamasho. At one point, he is caught and his body is modified like a mole cricket. After his long adventure, he is discovered by Kafuka and he then becomes a high school teacher. Students in the class start calling him "Left-wing Guerrilla" (apparently in lieu of "Pink Supervisor"), making him want to die again. Right before he jumps off a cliff, Kafuka suggests he "mock marry" a girl of the Holy Nosebleed Empire. A card reveals that the entire segment is a gag based on a summary from the jacket of the manga's first volume. In the second segment, Nami Hitō, who has been missing classes, finally decides to attend her school as no one really seems to notice her absence. Unfortunately, she does not get much attention from her classmates as the high school is full of extraordinary characters. At the end of the episode, most of the major characters are introduced and Nami is labeled as the 'ordinary girl' in the school.

The first part of this episode is supposed to follow this storyline from a chapter of the Zetsubō Sensei manga. Perry has come to the school on the anniversary of the school's founding. He is an American Commodore who known for opening up Japanese ports to foreign trade (in Japanese, the phrase "opening the school" (開校?) is pronounced the same as "opening the ports" (開港?)). After he opens up various things in the school, he tries to open up Nozomu Itoshiki's mind. Suddenly, Nozomu releases a mysterious wave that reveals the dark side of the world, which is full of despair. Finally, Perry learns the lesson that he shouldn't try to open up everything in the world. However, all the characters speak unintelligible gibberish, and the subtitles suggest that Perry is Son Goku looking for the Dragon Balls and that Nozomu is an alien bent on stopping him. In the next part of the episode, Nozomu is complaining about the over-decoration of various things in Japanese society. However, Kafuka Fūra denies it, saying that it is just a trend among stylish elites. In the next part, Nozomu meets his old time friend Ikkyū-san, who likes old things. They discuss together how old things are often ignored in modern Japan. Ultimately, he wants to obtain a former-surname by marrying Nozomu's sister Rin. Rin tries to escape from Ikkyū by calling her butler, but he ends up persuading Ikkyū-san to marry her. However, Kafuka manages to find out at the end that Nozomu and Ikkyū are not old friends, but rather one-day friends during the first day of school.

Harumi Fujiyoshi is listening to a Zetsubō Sensei radio show at home while working on her yaoi dōjinshi. The radio show is actually derived from a chapter of the Zetsubō Sensei manga, which portrays Japanese people's indifference to their ages and introduces a new character, Manami Ōkusa, who is a married high school student. In the second part of the episode, Nozomu criticizes the society where individuals are compelled to serve their 'duties' to meet other people's expectations. These 'duties' are often very superfluous and trivial. However, Kafuka points out the irony that Nozomu himself is a part of such a society, as the girls around him are expected to serve their various 'duties' to take care of their teacher. In the third part of the episode, Nozomu is in despair about society, where serious matters are often taken too lightly. Several of Nozumu's students provide their experiences of such a trend. After Rin Itoshiki makes an appearance as one of Nozomu's new students, Nozomu and his students decide to reverse the trend by treating various trivial matters with serious attitudes, which eventually becomes an addicting habit for everyone.

Nozomu Itoshiki and his students enjoy the festival of Tanabata and talk about instances where people pay more attention to the trivial details of many objects rather than the main subjects. In the middle of their conversation, which Ikkyū-san later joins, the alien race El Niño suddenly invades Japan with their mecha army. Fortunately, Chiri digs up an ancient mask and activates its hidden power to defeat the alien force. The aliens admits their mistake of paying attention to trivial aspects of Nozomu's students rather than the progress of their invasion. At the end, Nozomu and Ikkyū-san do not remember how Japan was saved from the alien invasion, as they were paying attention to trivial details of the battle scene. In the second part of the episode, Jun Kudō is reading books in the school library, while Nozumu is worried about Jun's desire to read everything in the world, which could eventually include Nozomu's own embarrassing mind. When Nozomu's other students visit the school library, Jun tells heart-warming stories that move every one of them to tears. Nozomu feels even more certain of Jun's ability to read people's minds, so he puts himself in a freezing room full of penguins to prevent Jun from reading the conclusion of the episode. The third part of the episode shows what happened between Nozomu's nephew, Majiru Itoshiki, and Kiri Komori while the alien invasion of the 'A Painter by the Roadside' episode was undergoing outside the house.

Nozomu Itoshiki and his students enjoy the festival of Tanabata and talk about instances where people pay more attention to the trivial details of many objects rather than the main subjects. In the middle of their conversation, which Ikkyū-san later joins, the alien race El Niño suddenly invades Japan with their mecha army. Fortunately, Chiri digs up an ancient mask and activates its hidden power to defeat the alien force. The aliens admits their mistake of paying attention to trivial aspects of Nozomu's students rather than the progress of their invasion. At the end, Nozomu and Ikkyū-san do not remember how Japan was saved from the alien invasion, as they were paying attention to trivial details of the battle scene. In the second part of the episode, Jun Kudō is reading books in the school library, while Nozumu is worried about Jun's desire to read everything in the world, which could eventually include Nozomu's own embarrassing mind. When Nozomu's other students visit the school library, Jun tells heart-warming stories that move every one of them to tears. Nozomu feels even more certain of Jun's ability to read people's minds, so he puts himself in a freezing room full of penguins to prevent Jun from reading the conclusion of the episode. The third part of the episode shows what happened between Nozomu's nephew, Majiru Itoshiki, and Kiri Komori while the alien invasion of the 'A Painter by the Roadside' episode was undergoing outside the house.

It's time to hand out grades, but Nozomu Itoshiki hands out completely censored report cards to his students, because he understands that majority of students do not want to be notified of their grades. He argues that people should have right to choose to be 'uninformed' of undesirable information, since they have right to be informed of desirable information. Ultimately, he tries to escape civilization to become 'free' of all the notifications in the world, but he is still in despair as nature are also trying to communicate with him. Meanwhile, Kafuka Fūra is admiring the all-knowing housewife in the neighborhood. In the second part of the episode, Nozomu Itoshiki and his nephew, Majiru, fall asleep together and have a dream where everyone's personality is reversed. The students in his dream realize that they will disappear when Nozomu wakes up, so they try to put him in an eternal sleep by murdering him in his dream. In the third part of the episode, Nozomu and his students discuss various things that are kept secret or unknown from their parents. During this section, the characters are voiced by numerous random voice actors (with most of them from the show itself), and are changed frequently.

Nozomu Itoshiki hands out an application for his pension in a government office, but an employee makes fun of Nozomu's name. Nozomu is sick of hearing the same thing about himself over a million times and he sympathizes with other people, who have experienced a similar situation for countless times in their life. Meanwhile, Harumi Fujiyoshi realizes that she is an extreme minority as no one seems to agree with her view. The second part of the episode shows a Zetsubō channel featuring a number of television programs such as audience survey, music show, magical girl anime, cooking show, etc. In the third part of the episode, Nozomu is kicked out of a café, because a Jyuken student is constantly irritated by him. The café manager kindly asks Nozomu to forgive him, because it is generally believed that exam-preparing students should be treated with the utmost care. Though Nozomu can't quite understand this kind of expectation in the Japanese society, he nevertheless tries to take advantage of this trend by becoming an exam-preparing student himself. Eventually, he happens to pass every certificate exams in the world except for one: an exam that tests whether a person is ready enough to commit suicide. However, he fails the exam and thus becomes not worthy enough to live nor worthy enough to die. The third part of the episode is shown using various animation techniques.

When Nozomu Itoshiki tries take photograph of his nephew and Kafuka Fūra in the public swimming pool, he is accused of being a spy by another woman. Nozomu blames the society, where everyone, including those who do not have any malicious intent, is suspected of being spy. Suddenly, Kafuka gives him a secret mission and Nozomu has to escapes from the greater suspicion by finding a good place to isolate himself. At the end, Kafuka devises a plan of 'positive counter intelligence' to help him out by leaking unreliable rumors such as urban legends to confuse everyone in the society. In the second part of the episode, Nozomu claims that pretentious side of everyone is ultimately exposed in May. At the end, many of Nozomu's students' hidden secrets are exposed, though some of them are merely his imagination. In the third part of the episode, many things in the world are not divided exactly half and half despite their claim. To correct such mistakes in the world, Chiri Kitsu enforce the ratio of everything into exactly 50/50 ratio, which produces various results at the end.

When everyone's mind isn't functioning well after the New Year, Maria decides to tackle them in a manzai fashion. Nozumu Itoshiki explains that there are things other than the New Year that causes people to feel groggy such as jet lag. Ultimately, Maria decides to tackle the government of Japan arguing that Japan isn't paying enough attention on its national security matter during the peace time while the neighborhood countries are posing as threat. In the second part of the episode, Nozomu Itoshiki suddenly decides to inspect students by surprise. In order to help Nozomu to achieve his goal, Maria and Chiri starts taking photographs of vulnerable private moments of students. Nozomu's colleague, Jinroku, is the only one able to withstand the inspection 24 hours a day. Suddenly, Kafuka Fūra argues back that being a careless person can be a great appeal as it can draw sympathetic feeling from everyone. Chiri suddenly decides to take advantage of this trend by becoming a careless person on purpose, but it consequently puts many characters in grave danger.

Nozomu Itoshiki watches a live baseball game and is reminded of a fact that many baseball stadiums intentionally reduce the flight range of baseball to make the game more enjoyable to watch. He suddenly realizes that such practices of intentional 'detuning' are quite popular in Japanese society. Nozomu points out that some people use 'detuning' as an excuse for their faults, Kafuka explains that people in general feels more comfortable with 'detuned' products rather than the cutting-edge one. In the second part of the episode, Nozomu states that there is an increasing tendency of saying 'not bad, not bad' at terrible things to comfort the victims. However, Nozomu explains that such instance can turn out to be a 'mini-propaganda', which could unknowingly mislead other people to believe in the same way. In the third part of the episode, Nozomu refuses to teach the first period class, because he was previously rejected by a restaurant in Kyoto as he was a first-time customer. He realzies that the Sayonara Zetsubō Sensei anime series could have been difficult series to approach for the first-time audience, so he decides to start the first-time-friendly episode. However, he is annoyed by the constant inquries from the first-time audiences. Thus, he decides to only invite regular audiences, but they seem to knows too much about the series. Ultimately, he decides to also reject the regular audience from the show.

Detective Nozomu Itoshiki is called upon by an investigator Jinroku to cooperate with the serial murder case, which took place in Sakebu Itoshiki's mansion. Sakebu was a famous artist, who was known for taking care of twelve girls in his mansion, but he has recently died of a chronic disease. After finding out that each murder resemebled various scenes of well-known anime, Nozomu initially suspects Kagerō Usui from his deduction. However, he later discovers the hidden truth behind the serial murder in Sakebu's underground storage room. In the second part of the episode, everyone is celebrating the Tanabata by hanging their written wishes on a bamboo tree, but Nozomu is initially doubtful about the Tanabata custom. However, Kafuka Fūra manages to convince him that every wish will eventually come true in the afterlife, even if it seems impossible to achieve in the current life. Suddenly, everyone in Tanabata festival is convinced of her idea, so they begin to form a cult based on her belief.

Nozomu Itoshiki teaches his students to get themselves used to summer vacation gradually as he believes that a sudden change of state is unhealthy for everyone. Suddenly, Nozomu is in despair, because there are too many instances of 'hard landings' in current society. In order to teach how to do a proper 'soft landing', he prepares a flight simulator for the students. In the second part of the episode, Nozomu meets a taxi driver, who is about to do the last driving before his retirement. However, he ends up paying ridiculous amount of taxi fee as he was unwillingly drawn to taxi driver's dramatic situation. Subsequently, Nozomu is constantly drawn to many other dramatic situations despite his desperate attempts of scape. In the third part of the episode, Nozomu discusses various instances of 'backward flow', where people are drawn to various interests in reverse way. While Nozomu considers phenomena of 'backward flow' quite embrassing, Kafuka argues that it is a manly thing to do like a wild salmon climbing the flowing river. Meanwhile, Chiri forces other people to approach their interests in proper way instead of the usual 'backward' way.

After dismissed from the school as a demon, Nozomu Itoshiki wonders where the devils will end up once they are dismissed from everyone. Nozomu suddenly argues that dismissed people should be provided with a new employment after their dismissal, otherwise dismissed people will end up being 'wild' people in the street. Nozomu's students brings various wild people to his house and ask him to take care of them. Nozomu flatly refuses the offer, but he cannot help but to take care of them. Unfortunately, Nozomu is fired from his school for his suspicious conduct and he himself becomes a 'wild' teacher. In the second part of the episode, Meru Otonashi's dad wants to find a suitable voice actor for her as she has inferiority complex of her voice. However, no one seems to have a voice that matches with Meru's character. After the failed audition, she goes throught a number of troubles thanks to the voice transmitter attached to her neck. In the third part of the episode, Nozomu complains that people seem to have too many statements on the premise of something as it is a serious breach of etiquette. While Nozomu makes a visit of a Tsundere cafe in Akihabara, he finds numerous instances where unnecessary premises are made. Moreover, Nozomu confronts an enemy character, but they end up being friends together on the premise that the anime series is indeed derived from a Shōnen manga.