Director James Gunn's badly behaved dog the inspiration for Superman's pet Krypto

About three years ago, American writer-director James Gunn was trying to figure out the arc of what would become his new blockbuster Superman.

- Esther Zuckerman

NEW YORK - Then he adopted a dog.

He named the scruffy rescue Ozu, after Yasujiro Ozu, the Japanese film-maker known for his serene works.

At about eight months old, Ozu the dog was not at all peaceful. After surviving a hoarding situation, it was fearful of humans and intensely destructive.

He chewed up furniture, shoes and even a US$10,000 (S$12,800) computer. He also ate a tampon out of a wastebasket, necessitating a trip to the vet.

Gunn realised that if Ozu had been superpowered, the damage would have been even worse.

"It was where Superman the movie came together for me," he said in a video call. The 58-year-old decided that his version of Superman would have not just a dog, but a bad dog who could fly.

He wrote the opening sequence in which Superman (David Corenswet), defeated for the first time, calls out to the canine Krypto to help drag him to the Fortress of Solitude.

Krypto — who, like Ozu, is poorly behaved — jumps all over his master, seemingly causing more pain before doing his duty.

Superman, which also stars Nicholas Hoult as the Man of Steel's nemesis Lex Luthor and Rachel Brosnahan as intrepid reporter Lois Lane, is now showing in cinemas.

"The universe we normally see Superman living in in movies is usually this lone, serious superhero and then people and then that's it," Gunn said. "This Superman exists in a different sort of universe where there are flying dogs."

But Ozu served as more than just inspiration. Gunn's pup also became the physical model for Krypto, who is computer-generated so he can do things like soar through the sky and attack villains.