A mother searches for her missing son after a devastating calamity, only to realize that she has died and is now confined to a realm of restless spirits.

Maye Sora, a 19-year-old university student living in Tokyo, receives news of her grandfather's death. Busy with moving with the help of her friends, she puts off confirming the news.

The story centers around a three-generation family and the memories of Hiroshima between 1975 and 2025. Back in 1975, Hiroshima is slowly rebuilding itself after the atomic building. There, lives Ogaki Sachie, a mother who survived the postwar era and single-handedly raise her two daughters while operating a local coffee house. Half a century later, in present-day Hiroshima, Sachie's granddaughter, Kuramochi Yuki, is now an employee at a local TV station and is assigned to produce a special program. She decides to talk to grandmother who brings up the untold past of Hiroshima for the first time.