A film about baby-switching by Japan's Kore-eda Hirokazu that ponders nature versus nurture premiered at the Cannes film festival on Saturday, joining an Iranian challenger as contenders for the top prize.
"Soshite Chichi Ni Naru" ("Like Father, Like Son") is one of two Japanese films out of the international roster of 20 vying to take home the Palme d'Or prize on May 26 from the world's largest film festival being held on the French Riviera.
Japan has won four times before, most recently in 1997 with Shohei Imamura's "Unagi" ("The Eel"). Its other offering this year is the stunt-filled police thriller "Wara No Tate" ("Shield of Straw") by Takashi Miike.
"Soshite Chichi Ni Naru" stars singer and actor Masaharu Fukuyama as workaholic Ryota who, along with his docile wife Midori, played by Machiko Ono, is grooming his 6-year-old son Keita for success.
Their outwardly picture-perfect family life is shattered one day after the hospital where Keita was born informs them they made a mistake and Keita is not their biological son.
"Why didn't I see it? I'm a mother!" laments Midori after the revelation, which forces the couple into an agonizing decision - whether to keep Keita as their own, or make a swap.
The film finds moments of humor and humanity when Ryota and Midori meet the couple, played by Yoko Maki and Lily Franky, who have brought up their biological son.
Shopkeepers from a different class, they horrify the sensibilities of Ryota, who sees them as bumbling simpletons incapable of rearing his son.
But the first impression is eclipsed by recognition of their kindness and obvious love for their children.
"I wanted to create this total upheaval in the morality of the main character," Kore-eda told journalists. "I wanted to create a real shock in his mind."
"Soshite Chichi Ni Naru" is Kore-eda's fourth film to compete at Cannes, his "Kuki Ningyo" ("Air Doll") having been included in the "Un Certain Regard" category for emerging directors in 2009.
Kore-eda's gentle film is a contrast to many over the first four days of competition that have been marked by violence.
Mexican film "Heli" includes a sickening torture sequence, while a man in Chinese film "Tian Zhu Ding" is driven to carry out a bloody rampage after failing to thwart corrupt officials.
"After suffering through a wash of nihilism in the official competition so far, it is a pleasure to experience a film-maker so at home to big-hearted humanism," wrote the Irish Times' Donald Clarke in a review.
A rival family drama, Le Passe ("The Past") by Iranian director Asghar Farhadi, also received critical praise after its premiere on Friday.
"The bookies probably still have Asghar Farhadi's The Past ahead in the race for the Palme d'Or," Clarke wrote.
He added that the warm reaction at a press screening of Kore-eda's film on Friday "suggests that the Japanese wizard may stand a sporting chance of taking home the trophy".