"The sound of the piano did not change even after the bombing!"

A tuner who was entrusted by the owner of the piano that was exposed to atomic bombing in Hiroshima on August 6, 1945. He himself is also a son of the father who was A-bomb victim. It is said that it is a piano that was bombarded at a close distance about 3 kilometers from the hypocenter. The tuner repairs and tunes A-bomb piano and places it on a 4 ton truck that he drives on his own. Nanako Eguchi(20), who grew up in Tokyo, studying early childhood education at university and aims to become a kindergarten teacher in the future, but is still vague about the future. Nanako happens to know the information of the A-bombed piano concert, and, when she checks it, knows that one of the A-bombed pianos is donated by her mother, Kumiko, and goes to see the A-bombed piano concert. The tuning master owns several A-bombed pianos, drives a 4-ton truck and travels all over Japan to continue the "A-bombed piano peace concert" activity. Nanako touches the broken piano, thinks something, and plays the keyboard. However, the sound does not come out beautifully. ... Nanako watches the piano and her own feelings. From her mother Kumiko who is a child of A-bomb victim, Nanako had neither been informed of Hiroshima tragedy in details nor her grandmother Chieko, a music lecturer, wanted to know about her grandmother, Hiroshima, and the A-bombed piano. She asked the piano tuner to accompany her on his truck as far as Hiroshima. On the way, in a parking area, young people having noticed the piano on the truck, the tuner explains to them that the piano is an A-bombed one and lets them play the piano, so Nanako has a valuableexperience. It is said that the mother’s family where her grandmother Chieko having passed away two years ago lived, is left as it used to be, and it will soon be destroyed by redevelopment of town. When her uncle brings Nanako to that house, she can follow a little by little her grandmother Chieko’s history from her old pictures, old musical scores, etc. Then her memory comes back that Nanako used to be loved by Chieko when Nanako was 5 years old. Why hasn't Nanako remember her grandmother Chieko since then? Why did Kumiko go out of Hiroshima? What did grandmother Chieko want to tell Nanako? Why is the piano tuner working on telling about the A-bombed pianos? Nanako visits the tuning workshop, and her heart moves when she sees the repair of her grandmother's piano. ... The tuner talks about his activities. He shows Nanako a rusty old dagger, which connected to the father's life when he was saved thanks to the dagger inserted aside when the father of the tuner was exposed to a fire station just 800 meters from the devil's heart. It is that dagger. That is why the tuner tells Nanako that his family is the origin of his activity. Nanako follows her roots and goes on to find something important while following the activities of the A-bombed piano. And when she is told that the tuner will do a concert of the A-bombed piano in front of the A-bombed Aogiri tree in the corner of the Peace Memorial Park on August 6 and she makes some determination....

昭和 20 年 8 月 6 日に広島で被爆したピアノを持ち主から託された調律師・矢川光則（佐野史郎）。彼自身も被爆二世。

爆心地から 3 キロ以内で被爆したピアノは被爆ピアノと呼ばれる。

矢川は、現在数台の被爆ピアノを託され修理。調律して、それを自ら運転する 4 トントラックに載せて全国を回る。

東京で生まれた江口菜々子（武藤十夢）は大学で幼児教育を学び幼稚園教師を目指しているものの将来について漠然としている。

被爆ピアノの一台を母・久美子（森口瑤子）が寄贈していたことを知った菜々子は、被爆ピアノコンサートに行き、矢川と出会う。

矢川を通して被爆ピアノ、広島のことを考えるようになり、祖母のことを知るうちに自身のルーツを探していく。

母・久美子はどうして広島から出て行ったのか？

祖母・千恵子が菜々子に伝えたかったこととは？

調律師・矢川がなぜ被爆ピアノを伝える活動をしているのか？

菜々子はルーツを辿り、被爆ピアノの活動を辿りながら次第に何かを見つけていく…