January 2118. Chief Inspector of the Criminal Investigation Department, Akane Tsunemori, receives a report of an incident on a foreign vessel – the body of Professor Milicia Stronskaya has been discovered. Behind the incident is a group known as the Peacebreakers, a foreign paramilitary organization and a new outside threat who are targeting the professor's research papers known as the "Stronskaya Document". Reunited with Shinya Kogami, a former fugitive from the Criminal Investigation Department, Akane grapples with a case that quickly escalates beyond their expectations. The Stronskaya Papers could reveal a truth that would shake Japan's government, and even the Sibyl System, to the core. It is in this untold story that the missing link is revealed.

After living together for three years, Misaki Takahashi and Akihiko "Usagi" Usami's relationship has been progressing smoothly. However, all great relationships have problems, and theirs is just beginning. With a new rival on the horizon, Usagi worries about Misaki's feelings towards him. Meanwhile, Ryuuichirou Isaka has always loved to intrude on Misaki and Usagi's love life, but his own love life hasn't been all smooth sailing—Isaka and his secretary Kaoru Asahina have been dating for a few years; however, Asahina prefers to keep their professional and private lives separate, often leading to troubled waters between them. As for Nowaki Kusama and Hiroki Kamijou, now that their careers are finally taking off, they hardly see each other anymore. With the time they spend together lessening, doubts and insecurities threaten to creep in between them. On the other hand, the 17-year age gap between Shinobu Takatsuki and You Miyagi has been a constant barrier in their relationship, but as they learn more about each other, their self-consciousness continues to fade. The beloved couples of Junjou Romantica, Junjou Egoist, and Junjou Terrorist are back again, this time with a new addition: Junjou Mistake!

Tsubasa Kazanari and Kanade Amou—the idol duo known as Zwei Wing—use their songs to power ancient weapons known as "symphogears" to combat a deadly alien race called the "Noise." While the general public is aware of the Noise's existence, knowledge of the symphogears are kept a secret. When the Noise attack one of Zwei Wing's concerts, Kanade sacrifices herself to protect a young girl named Hibiki Tachibana, leaving Tsubasa devastated and a fragment of her symphogear embedded within Hibiki. Two years pass and Hibiki is once again dragged into a Noise attack. While rescuing a young girl who has been left behind during the evacuation, she awakens the power of Kanade's symphogear lying within her. Although Tsubasa still grieves over the loss of Kanade, both girls must now learn to work together using their powers to defend humanity against the Noise. [Written by MAL Rewrite]

During a winter walk, Natsume meets a snowman youkai who is searching for something she's lost and can't seem to recall and decides to help her despite not knowing what exactly she's looking for.