A pioneering roboticist awakens in 2025 after decades in cryosleep. To change the past and reunite with his adopted sister, he seeks a way back to 1995.

After the death of his wife, Kenzaburō receives an unexpected letter from beyond the grave. His late wife asks him to travel to Lake Windermere in England with their son to scatter her ashes. Plagued by sweet and painful memories of his wife, Kenzaburō travels to England from Tokyo to fulfill her final wish, but the father and son's fraught relationship threatens to upend their journey.