In addition to films about death (“After Life”) and families (“Still Walking”), the Japanese filmmaker Hirokazu Koreeda has made several films about children. “Nobody Knows” looks at a group of kids who spent months on their own after being abandoned by their mother; “I Wish” concerns a boy trying to reconnect with his brother after his parents split up. His latest, “Like Father, Like Son,” examines a true case that occurred four decades ago in Japan, where many kids were switched at birth, a fact discovered much later. In every case, the child was put in the care of their blood parents. But in Koreeda’s film, both parents involved in a similar situation don’t know what to do: surrender the boy they’ve raised for years as their own or continue raising a child who’s not theirs.
You’ve said this film is inspired by personal experiences, but not that you had a child switched at birth.
I work on films every day. When I made “I Wish,” my daughter was three years old. I was away from home for about a month and a half. When I came home we were both a little bit nervous to be around eachother. We weren’t very close. The next morning when I was leaving the house, she said, “Come back and visit us!” I was shocked. It made me realize she doesn’t see me as someone who lives with her. I realized I needed to rectify this. It also made me realize that, even though we have a blood relationship, it’s important to spend time with her.
Did bits of your life wind up in the film?
There’s a part where he notices his son has taken pictures of him on his camera without him noticing. That’s based on my own experiences. When I was at work one day, looking at my phone, I noticed a couple pictures of me sleeping. It was shocking to me. There’s a different version of me [in the photos]. They’re what I represent to her.
Your film seems to suggest that, as opposed to 40 years ago, the decision on what to do with this kind of situation isn’t so clear-cut.
I think people might prioritize the time they spent with a child as opposed to favoring the blood relationship. That could be a possibility. But I still think the blood line would be seen as more important. We don’t have a very active adoption system, which may be a reason for that. The main character here prioritizes blood — but he also couldn’t give up the thought of the time he had spent with the son he raised.
What is your approach in terms of writing? Do your films tend to be much different from the script?
I make discoveries all over the course of production. I’d say my initial script is 50 percent of what it’s going to be. When I’m doing the casting it changes, especially with children. Based on my communication with them, I change some of the words in the script. I’ll use their vocabulary and put it into their lines. Until we wrap, I’m making changes. A film is a living thing.
“Like Father, Like Son” feels slightly different from your other films. It’s more story-bound, where the others sometimes moved around more freely.
My process since “Nobody Knows” has been the same, which is that I’ll change things while filming. But I think you’re right: The story here is my most composed and more tightly put together. There’s almost a propulsive force moving the story along. If there was a scene that didn’t necessarily have an involvement in the story, I took it out. Only those that were related to the story were kept in.