This Japanese drama presents a fascinating what-if: After years of raising their son, a well-off couple are confronted with the truth that their child was switched at birth. The parents can’t believe they didn’t somehow “know” he wasn’t their biological son. But that’s just what gets the ball rolling here, as the well-off couple meet the working-class family who have actually raised their son and experience the growing pains of saying goodbye to a child they love as their own and hello to a child of their own who’s a complete stranger. This is as good a time as any to familiarize yourself with the thought-provoking work of director Hirokazu Koreeda. The bonds of family run deep in his work, particularly over the past decade, helping him become one of the essential filmmakers of Asian cinema.