It’s 1940, and the population of Japan is divided over its entry into World War II. Satoko, the wife of a fabric merchant, is devoted to her husband but is beginning to suspect he’s up to something. Soon she allows herself to be drawn into a game in which she enigmatically conceals her intentions.

When lightning strikes a theater about to close its doors, three moviegoers are thrust back in time to the world inside the screen.

Mobile Suit Gundam G40 is a 2020 original net animation (ONA) by Sunrise and LDH made to promote the HG 1/144 Gundam G40 (Industrial Design Ver.), a collaboration between Ken Okuyama Design and the Bandai Hobby Center as part of the 40th anniversary celebration of the Gundam franchise. It depicts an abridged retelling of the One Year War, re-imagining iconic scenes from Mobile Suit Gundam with new designs.

1940, Kawamoto Akiko lives in Hiroshima with her father and mother, Genkichi and Shizuko, as well as her two younger brothers. Akiko loves playing her favourite piano. As the war situation worsens, she is busy helping out the war efforts. On the morning of August 6, 1945, she disobeys her father and heads into the centre of town for work. In Hiroshima 75 years later, her favourite piano remains, restored and playable following its survival of the atomic bombing

Yuki Ozawa is approaching her 50's and she has now began working on her first serialized manga. The theme of her manga will be based on her mother's personal war experience, who was only a 12 year old girl at that time. Yuki wants to create a piece that will pass down the memories of war to the future generations. With her editor, Sato, she goes to Nagoya to visit her mother, Ai (Ozawaai) to learn more about her mother's experience. At first, her mother reacts negatively to Yuki's request but soon she begins recalling her memories of love, life and the lives that were lost because of the air raids over Nagoya.