The story of the film begins after the events of the second season, at the graduation ceremony of the third-year students. Knowing that the graduation of the third-year members means the end of μ’s, the nine girls take a walk around the school filled with memories. However, when the students attempt to leave the school gates, a single email is sent to them, and the curtain on a new story for μ’s begins.

In the aftermath of the most devastating conflict mankind had ever experienced, the tiny island of Shikotan became part of the Sakhalin Oblast… and on the unhealed border in this remote corner of the world, friendship among children from two different countries timidly blossomed, striving to overcome language barriers and the waves of history. Inspired by true events.