ACCA—a national body of the kingdom of Dowa that provides public services to the citizens of the country—was established as part of the peace settlement between the king of Dowa and the 13 states of the country during a revolt. One hundred years later, Dowa is in a period of unprecedented peace, due in part to the ACCA system. However, rumors of a coup d'état start to surface. Jean Otus, the second-in-command of the inspection department of ACCA, is charged with inspecting all 13 state branches. What will he discover as he performs his audit? Intriguing and mysterious, ACCA: 13-ku Kansatsu-ka is a politically-themed mystery that reveals a world of diverse cultures and lifestyles, with intricate connections between its characters, as the truth of the coup d'état slowly unfolds.

Sana is not an ordinary little girl; she possesses a special ability known as Alice's Dream. Due to her power, which allows her to create anything from her imagination, all that she knows is the laboratory where she is a test subject. Wishing to experience the outside world, she escapes and meets a stubborn old florist named Zouroku Kashimura in a convenience store. All too soon, her pursuers catch up and Zouroku is roped into Sana's troubles. However, far from trying to distance himself, Zouroku extends a hand to help Sana. Following his values and sense of justice, he even gives the pursuers a piece of his mind! Zouroku then offers Sana a place to stay, beginning the daily life and struggles of the unlikely duo.

While most young girls make an effort to show off their feminine charms, Futaba Yoshioka deliberately behaves like she wants to repel anyone who might be attracted to her. Ostracized by her female classmates in middle school for being a little too popular with the boys, she desperately strives to avoid a similar situation in high school by being unnecessarily noisy and graceless. Nevertheless, scattered among Futaba's unpleasant memories are the treasured moments with the boy she had a crush on, Kou Tanaka. Unfortunately, that spell abruptly ended on a sour note when he suddenly stopped attending school and never came back. When Futaba finds out that Kou has returned—with a different last name this time—she can already feel the butterflies in her stomach. However, Kou Mabuchi is not the warm boy that she remembers from her days in middle school; he is now taller, more charismatic and withdrawn—making him far less approachable. Futaba believes that if she returns to her former self, Kou will begin to take notice of her again. But is she prepared to sacrifice her bubble of normalcy and risk losing her friends in the process?

As New Year’s Eve draws closer, preparations for a holiday party are underway in Petersburg. In anticipation of the event, Eila Ilmatar Juutilainen of the 501st Joint Fighter Wing is determined to take Sanya V. Litvyak on a leisurely walk around the city. However, despite Eila's best intentions, she gets interrupted every time she gets a chance to ask Sanya out, ruining the moment and separating the girls. To make things worse, a Neuroi is approaching the base, threatening both the squadmates and the celebration in Petersburg.