Lala is a girl from the Memory Clan, a group of enchanted beings who visit humans who have died or are close to death to collect and preserve their memories. This is their sole purpose, and no two human lives are the same. Lala is fascinated by humans and their stories, but her older sister Aridera, the clan's singer, reminds her of the clan's fundamental rule: they must never become directly involved in human affairs. Lala struggles to understand this prohibition, and her innocent curiosity about why she cannot engage with humans gradually transforms her way of life.

Lala lives in a world where death is accompanied by these memory collectors, and reapers also exist. The setting blends elements of fantasy with a melancholic, reflective atmosphere focused on the moments surrounding a person's death. The narrative follows Lala as she carries out her work of gathering memories, each representing a unique and diverse life path.

A major narrative arc begins when Aridera one day suddenly loses all of her collected "death memories" and ceases all life activity, becoming frozen and immobile. Desperate to save her sister, Lala sets out and encounters a stray reaper and a girl in the snow. This event forces Lala to confront the identity of whoever stole the memories, the secrets Aridera was hiding, and the true meaning behind the rule forbidding contact with humans. The story weaves together the experiences of Lala, her sister, and the reapers as they explore the meaning of life, death, and memory.