Mamoru Hosoda is one of the greats of Japanese animation, whose films like "The Boy and the Beast" and "The Girl who Leapt Through Time" are seen as modern classics.
But he admits he wasn't the greatest father in the world to his first child. And his wife told him so.
"When my son was born I was working on 'The Boy and the Beast' and I was hardly at home. I relied an awful lot on my wife," Hosoda told AFP as he premiered his charming new movie "Mirai, My Little Sister" at the Cannes film festival.
"My wife still says that she brought my son up on her own. So she said to me, 'Are you going to be the same for the second child?'
"That really made me think. I wanted to bring up the children, so I changed," said the director whose films regularly top the box office in Japan and beyond.
The result is "Mirai", an often hilarious study of overstretched parents and toddler temper tantrums that came out of the time Hosoda tried to work at home after the birth of his daughter.
"A lot of what you see in the film really happened," Hosoda admitted, "especially after our second child was born. The stuff between the children and the conversations between the couple are very close to our experience."
Indeed, the antics of the film's four-year-old hero, Kun, who is sent into a spiral of jealousy by the arrival of his little sister, will ring bells with most parents.
- Hapless 'new man' -
As will the strains parenthood can put on couples, as the architect father agrees to work from home while the busy executive mother tries to make up for lost time at work.
Failing completely to balance the household chores, the father further irritates his wife by pretending to be the perfect new man in front of their admiring neighbours.
Trying not to fight in front of the children is one thing, but we should not lie to them either, Hosoda believes.
"If in the film you see the parents saying what they really think in some situations, it is because I did not want to lie to children. I wanted them to know what adults think. Maybe that is why it amuses the grown-ups so much," he said.
"If you want children to trust you, you should not lie to them. Long ago parents played the role of being the parent. Today that game no longer works, because the family has changed a lot."
"Japan may seem like a conservative country but the roles within a couple, and what constitutes a family, are changing."
Hosoda said the family has become the big theme of his work, particularly since his fantastical "The Boy and the Beast" became a worldwide hit.
- The family is changing -
"It asked how you become a father. My first child had just been born and it shows someone who does not know how to be a father.
"I have made some progress since," Hosoda laughed. "This film is how to be one..."
"The family has become my subject because it is changing and we don't know where we are going. That is why I wanted to tell these stories."
Fatherhood has also changed Hosoda's approach to storytelling.
"My son never stops asking us to read to him -- though it was mostly my wife who does it. When we run out of books from the library we just open our hands as if they were a book and make up a story.
"We call it the 'Books of the Hands'. And it's been good and fun for me to have to improvise like this."
Just as in "The Boy and The Beast", Hosoda uses fantasy sequences and time travel in "Mirai" to flit the little boy up and down his family tree to his own parents' and grandparents' childhoods.
"I wanted to tell a big story from a little one," he told AFP, recounting the recent history of Japan through the shared experiences of one family.
"It's the big cycle of life. Spending time with my children made me remember my own childhood. It is almost as if I am reliving it," he said.
"Mirai" has been snapped up by US, Canadian, British and other European distributors at Cannes and will be released in Japan in July and elsewhere later.