The world has been divided into two halves by a giant wall to prevent the epidemic of "Dark mist". In order to shelter the refugees, artificial cities called "Arks" were built. Shido Enishi is a private detective, who works at the ninth Ark. One day, he is asked to capture a burglar. The seemingly simple case leads him to a great conspiracy.

The visual features the tagline, "I met you in my 17th summer ..." The "boy-meets-girl" story depicts how words and music bridge the gap between Cherry, a boy who is terrible at communicating with other people, and Smile, a girl who hides behind a mask. They meet in a mundane suburban shopping mall in a provincial city. Cherry always wears headphones and puts the feelings he cannot utter into his hobby, Japanese haiku poems. Smile always wears a mask to conceal her large front teeth, for which she has dental braces. As a popular video star, she streams a video about seeking "cuteness." (Source: ANN)

Optimums, a terrorist organization, maintains an oppressive regime over Sacco City—a place where thousands of immigrants reside. Since they came into power a year ago, the organization has enacted new laws and reclassified the immigrants from the far east as East Refugees. He Jiang is a hot-tempered girl who travels alongside her father, He Chang Feng, as he delivers goods across Sacco City in their truck. One day, the Klee—a military police force—apprehends both for being in possession of a sword. In the ensuing struggle, He Chang Feng is shot dead while his daughter is imprisoned for eight years. Finally released from prison at the age of 24, He Jiang, with the help of her new friends, finds her abandoned truck and repairs it. As she begins delivering goods around the city once more, she faces various hurdles. With the Department of Security discriminating against her and the other East Refugees, He Jiang is forced to fight back, but she will need to gain more allies if she wants to stand a chance.