Keita has two older step-sisters, Ako and Riko, but since they aren't related by blood, they love him in a lustful way. After a mishap at school, Ako and Riko finally confess their love to him. Keita dislikes the thought of seeing them other than brother and sister, but as he tries to enter the same school as his sisters, he slowly becomes attracted to them.
The story is set in the same Hinamizawa village of the previous stories. The village has been completely sealed off due to a mysterious virus in 1983, and Maebara Keiichi and Ryuuguu Rena deal with the outbreak.
While waiting for Komachi to prepare breakfast, Hachiman ponders on the institution of marriage with his opinion entailing that people deceive themselves into thinking that it makes them happy while they go about its compulsory activities. As Komachi teases that Hachiman's opinion would be unlikely to get him married, he deduces that having a little sister to take care of their sibling to be the same as being married. After school Shizuka enlists the Service Club to help her prepare a magazine as part of a campaign by the Chiba region to promote "Love and Marriage" to teenagers. Hachiman and Yukino start brainstorming ideas which turn out to be too complex for average high schoolers to understand. However Yui suggests that they conduct a marriage survey in class 2F. However the broad answers that 2F provides only seem to emphasize their inexperience in such things, which prompts Yukino to call in Komachi who has a similar experience when taking care of Hachiman. Komachi suggests that they refocus the project on how to be a better wife and has Shizuka, Yui and Yukino compete in contests she makes up. During the first cook-off contest, Hachiman praises Shizuka's cooking prowess. During the second bridal quiz contest, Komachi presents a series of scenarios to Shizuka, Yukino, Yui and Hachiman. During the last bridal dress contest, Hachiman compliments Shizuka's beauty and Komachi is forced to award her as victor of the competition. Afterwards, the Service Club starts preparing their findings for the magazine, with Hachiman lagging behind because of his workload, much to Yukino's annoyance. Finally as Hachiman prepares his article, he writes that since no amount of preparation can really prepare someone for the unforeseen future, he advises female readers to stake their claim on their desired husbands since everyone deserves the right to be happy.
The story of the original manga begins after 70% of the moon was suddenly vaporized in an explosion. The super lifeform responsible for this catastrophe is a strange tentacled creature that can slink around at supersonic Mach 20 speeds. It has a 10 billion yen (US$100 million) price on its head, but for some reason, this creature ends up teaching a middle school class at the beginning of the school year. The students have until graduation to assassinate the teacher, or it will destroy Earth as well.
The event anime special will adapt the original manga's popular segment about the field trip to ancient Kyoto.
Naruto: Shippuuden - Jump Super Anime Tour 2013 Special
"Tsuki ni Naku" will take the story content from volume 11 of the manga, which tells the story of when land god Yuuhi meets his companion Mariabelle. This OVA is bundled with the limited edition of the manga (14th, 15th, and 16th).
It is the start of Takatoshi Tsuda's second year as the put-upon vice president of the student council and his sister Kotomi is entering school as a first year. New friends and double entendres are made.