16 years ago, since the “Law for Public Order and Morals in Healthy Child-Raising” policy was established, the use of indecent words became prohibited throughout Japan. Okuma Tanukichi, out of admiration for Anna who serves as the student council president, decides to enter the country’s leading elite ‘public morals’ school. He then meets “Blue Snow”, a terrorist who gets hold of his weakness, leaving him no choice but to become a member of “SOX”, a (sexually healthy) terrorist group. Is that prison over there? And also, harem?

Okuma Tanukichi, whose wish was to become like Anna who was healthy and pure, regretted being one of the causes leading to the huge success by SOX. However, he actually felt good inside and his heart went ‘dokun dokun’. And so, on the day when they had physical examination, they once again planned new perverted terrorism activities.

Saotome Otome happens to see Tanukichi’s true identity as a terrorist. Because of that, he is brought into the SM world as a threat. For that reason, Tanukichi, whose crotch is like a campfire volcano, completely did not notice that Anna was troubled by a stalker who has been secretly taking photos of her and sending letters to her. And so, he has a certain discussion with Otome...

After spending time in the hospital following the events at the park, Ayame tells him that she has persuaded Otome to join SOX in hopes of making more risque artwork, even finding ways to draw that the PMs can't detect, but Otome still requires Anna as an inspiration. Tanukichi soon returns to school, but Ayame is strangely absent and Anna keeps avoiding him. Later, Ayame talks about her latest plan to reclaim a hidden stash of old pornographic material located on private property. She can't do it alone, so instead she plans to lure the students from school out to the property during the weekend. However, her plans are sidelined when Tanukichi is targeted by a stalker and Anna's mother, Sophia, shows up to the school in person to get the students to support her new legislation that would force all students to wear chastity belt-like devices. Running low on options, Ayame decides to have Tanukichi confront his stalker while Otome hides in a closet to draw lewd pictures herself. However, the stalker turns out to be Anna who restrains and assaults Tanukichi while being unable to understand her feelings. After Ayame accidentally interrupts them, Anna flees as Otome begins furiously drawing the scene with her teeth. Later that night, Hyouka confronts Anna in the lobby of her apartment, asking why her science lab was sterilized without asking. Anna responds that it was done out of love, as the more "impure" influences she eliminates, the more she will be rewarded with love, therefore everything she does for love is just.

Ayame tasks Tanukichi with distributing Otome's new pornographic artwork to the students along with a map to Yotsuga Forest. However, Tanukichi finds himself targeted by an increasingly-obsessive Anna around school, trying to make him drink her "love nectar," and drink from Tanukichi's. While escaping from Anna, he accidentally drops his bag filled with illegal material in Hyouka's lab and tells Ayame that he can't distribute them with Anna constantly trying to pin him down. On Sunday, the day of the "X Prohibition Law" signature drive, Sophia plans to greet the students of her daughter's academy in person and Ayame plans to quixotically storm the forest against a large force of morality police. Surprisingly, the students all show up at the forest, as Hyouka picked up Tanukichi's material and quietly spread copies around school herself. She manages to distract the police long enough for the female students and SOX to start looking for the hidden stash of porn. However, Anna shows up in person, chasing down Ayame in her Blue Snow disguise. Ayame tosses Tanukichi down into the forest to help him escape from Anna, where he finds the porn stash in a suggestively-shaped cave. However, when he hears Ayame being strangled by Anna, he decides to save her wearing a new disguise he found in the cave. Anna can't understand why the new terrorist gives her similar feelings to Tanukichi, and leaps into the forest in shame. Later that night, Sophia holds a press conference announcing the success of the petition drive, but discovers too late that someone replaced her signed petitions with pornographic artwork, which gets broadcast live around the country and embarrasses her push for the new law.

As Otome's hentai drawings spread around the school, Ayame decides to take the next step and make masturbation aids in the kitchen of the cafe SOX regularly gathers at. Tanukichi is assigned the task of getting Hyouka to develop small vibrators, but upon coming to collect one, a mostly-naked Hyouka attempts to learn about his "cucumber" as payment for her services. While they argue, Anna stops by and starts growing jealous, so Tanukichi quickly hands her a finished vibrating egg without telling her its true purpose to calm her down. The next day, Tanukichi accidentally activates the vibrator with the wireless remote Hyouka gave him, reawakening Anna's lust. Tanukichi tries desperately to escape or find a way to turn off the vibrator, but none of his friends want to help him, and Anna finally traps him inside the Student Council room. Tanukichi discovers that Anna turned the vibrator into a pendant, but is unable to reach it while being pinned down under her. Eventually, the vibrator shorts out as Anna climaxes and Tanukichi manages to escape. Later, Anna overhears Otome make a dirty remark about Tanukichi and starts strangling him while Ayame refuses to help.

SOX forms alliances with other erotic terrorist groups throughout Japan to share various pornographic books with each other. Back at school, the student council discovers that someone has been stealing the underwear of girls and boys throughout the city and crediting SOX with the heists. Tanukichi and Ayame watch a girls' changing room to catch a thief, but when Ayame runs off, Anna appears to sexually assault Tanukichi again. Shortly after that, Tanukichi reunites with Ayame only to find her speaking with Hyouka, and confiscates her yaoi book with characters loosely based off himself and Goriki on the cover.

Tanukichi wakes up to find Kosuri sleeping next to him and Anna dangerously holding a knife in his doorway. He quickly decides to pretend Kosuri is his little sister, but it backfires as Anna threatens to stab her, cutting a large hole in his floor before leaving. Later at school, Anna's father has sent Oboro Tsukimigusa to become the school's Prefect and take charge of the effort to eliminate impure influences in school. However, unlike the moral authorities, Oboro starts by removing mundane items like basketball hoops and volleyball nets as they may somehow lead boys to immoral thoughts.

Ayame launches an operation at school to try and sabotage both the school Prefect program and Gathered Fabric at the same time. First, she uses her Blue Snow persona to spread more lewd drawing materials throughout school while Tanukichi will hang his used boxers to try and attract Gathered Fabric, then take out the underpants thieves to show that SOX does not support them. However, Anna and Oboro come through the door instead. Anna again assaults Tanukichi, and he begs for help from Oboro but she offers none, claiming that even though the act may be immoral, she was trained not to interfere if Anna herself acts immorally.

As SOX makes negotiations with White Peak to stop hunting down Gathered Fabric members, Their negotiations fall through as Ayame chastises him for using erotic terrorism as a front for the panty thefts. The next morning as Tanukichi rushes to school on a bus due to the broken monorail, Goriki tells him that somebody cut the monorail's power lines, to which he suspects the antics of Gathered Fabric. While talking to Ayame however, Tanukichi and Goriki's bus becomes hijacked by a Gathered Fabric member. Among the jacked buses, Hyouka, Anna and Oboro, and Otome are in separate buses, with White Peak holding Otome's bus hostage. During his bus jacking, White Peak also hijacks the PM systems and proclaims war and his organization as an affiliate with SOX. As Hyouka is interrupted watching the news, she questions the Gathered Fabric member about panties, to which she is threatened by a gun, in which she identifies is a fake. As a result, the jacker is quickly subdued by the bus passengers, and Hyouka receives praise for her actions, although quickly dismissing their words. Meanwhile in Anna and Oboro's bus, as their jacker is collecting everybody's undergarments, Anna single-handedly beats him down, prompting fearful reactions from the male passengers (except for Oboro). On Tanukichi and Goriki's bus, as Goriki is about to give up his undergarments, he causes everybody to vomit in the bus, including the jacker and even the driver who saw him in women's underwear. As Tanukichi escapes, Ayame finds a leak in White Peak's true identity: Takuma Ichinose. She also finds out that there is a real gun among the fakes, to which Hyouka is monitoring. To apprehend Takuma, Ayame has Kosuri gather white panties and lure out Takuma's bus. Despite Tanukichi using musk panties to mask and protect himself, He is overpowered by Takuma, who becomes empowered (and turned on) by the scent. After Ayame intervenes, he is thrown off by Ayame's own scent infused in her panty mask, which allows Ta

As Kosuri points her stun gun at Tanukichi, he has no choice but to flee the bus, and he is chased further by the Decency Squad. After Kosuri helps out Takuma, they proceed to take the hostages to Zoshigaoka Academy. After managing to evade the Decency Squad, Tanukichi is approached by Hyouka, who shows him a breaking news story where 39 buses holding 500 hostages are being taken to Zoshigaoka Academy. At the school, the members of Gathered Fabric are making ransom demands with food and drinks as well as new panties, at the cost of provocative images of the students wearing panties on their heads if they fail to comply. As the students put on fresh pairs of panties to mark with their scent, Otome becomes excited at the sight and starts drawing with her mouth, to which she drops her pencil and stumbles across a box of paint. Meanwhile, Ayame and Tanukichi assess the dire situation at hand, to which SOX's blame in this incident will have society see them as criminals, and that the only way to clear SOX's name is to have them capture White Peak, lacking the numbers to do so. As Tanukichi is awkwardly approached again by Hyouka, she explains how people like Anna are brainwashed to believe that anything they do is "righteous" and fall into insanity. Reminded of Anna, Tanukichi devises a risky plan that if successful, can take down Takuma. While Kosuri devises tactics for Gathered Fabric, Takuma reveals that he had no intentions of a revolution or warfare or even wanting to escape. Betrayed, Kosuri tries to immobilize him with her stun gun, which fails due to the wine-stained underwear covering his body from the shock. Later, Otome calls Tanukichi, who manages to escape by drawing 3-D perception art of her and the hostages, telling him Takuma's and the other hostages' location. As Tanukichi executes his plan, Takuma is about to receive his third set of panties, until Ayame, Tanukichi, and Anna step in, as well as Goriki and Oboro. Tanukichi reveals that his plan was to ge

SOX receives a mysterious invitation to a "health spa" where they come face to face with some stiff competition, but in the midst of battle an erotic secret is revealed!