Misaki Takahashi is a regular high school student who is preparing for his university entrance exams. In order to reduce the stress of studying, or so he hopes, he accepts the help of his older brother's best friend, and famous author, Akihiko Usami. However, Masaki is about to find out that Usami's books are of a very naughty genre, and that there may be something naughty waking up inside Masaki as well. Junjou Romantica also follows the story of two other couples loosely connected to Masaki and Usami's "Romantica." Egoist shows the very passionate, but often complicated, relationship between university professor Hiroki Kamijou (whose life has reached an all time low) and paediatrician Nowaki Kusama, who falls for Hiroki at first sight and would do anything to make him happy. The third story, "Terrorist," shows just how obsessive love can become when rich eighteen-year-old Shinobu Takatsuki finally discovers something that he cannot have so easily—the literature professor You Miyagi. There is passion abound as these three couples try to achieve their goals in life while also falling into temptation and anguish with their partners.

During the 21st century, humanity attempted to colonize Mars by sending two species which could endure the harsh environment of the planet to terraform it—algae and cockroaches. However, they did not anticipate the species' remarkable ability to adapt. Now in the 26th century, a lethal disease known as the Alien Engine Virus has arrived on Earth, and the cure is suspected to be found only on Mars. The problem is, Mars in the present is overrun by creatures known as "Terraformars," incredibly powerful and intelligent humanoid cockroaches that mutated from those originally sent to the planet. The Annex I team, consisting of a hundred men and women genetically enhanced with characteristics of powerful organisms from earth, has been sent to Mars on a mission to find the cause of the Alien Engine Virus and to help cure humanity—signalling the start of the crew's fight for survival. [Written by MAL Rewrite]

In the small village of Hinamizawa, Rika Furude and her friends live together in relative harmony. Beneath this mask of peace, however, lies a hidden darkness, one that Rika understands all too well. In this eternal summer, she has been witness to unspeakable horrors. Every time the clock resets, Rika must try to find the villain behind these senseless deaths before tragedy strikes again. However, trying to decipher a mystery when only half the clues are present proves time and again to be disastrous, and each time she believes that things will change, she inevitably fails. As the annual festival approaches, Rika begins her descent from hope to despair in her struggle to break the chains of fate entangling them all. [Written by MAL Rewrite]

As with its prequel, Zoku Natsume Yuujinchou is about Takashi Natsume, a boy who has had the ability to see youkai since he was young, and his bodyguard youkai Madara, nicknamed Nyanko-sensei. Natsume attempts to return names written in his "Book of Friends" (which he inherited from his grandmother Reiko) to youkai in his village. Throughout these adventures, he meets some youkai that are friendly, some that want to steal the Book, and some that want to kill him, as Natsume learns about himself and his relationship with these mysterious beings along the way.