In the far future on a cold and snowy planet, an aging woman seeks a successor to her role as Kunchen: a bearer of memory for her people across generations, a role in which one must live a long and lonely life punctuated by decade-long cryosleeps.

In the far future, a thousand people are the only survivors of humanity, as Earth has been destroyed by an asteroid. Aboard a generation ship headed to a new solar system, a young Japanese man recounts the defining moments from his childhood.