In this documentary, Alex trusts his twin, Marcus, to tell him about his past after he loses his memory. But Marcus is hiding a dark family secret.

While the Second World War rages, the teenage Mahito, haunted by his mother's tragic death, is relocated from Tokyo to the serene rural home of his new stepmother Natsuko, a woman who bears a striking resemblance to the boy's mother. As he tries to adjust, this strange new world grows even stranger following the appearance of a persistent gray heron, who perplexes and bedevils Mahito, dubbing him the "long-awaited one."