Celebrated Japanese animator Hayao Miyazaki won his second Oscar on Sunday with "The Boy and the Heron" -- the Studio Ghibli co-founder's first film in a decade, and potentially his last.

The film, about a boy who moves to the countryside during World War II, won best animated feature, the same award scooped in 2003 by Miyazaki's "Spirited Away".

It bested top rival "Spider-Man: Across the Spider-Verse", Disney's "Elemental", Netflix's "Nimona" and the dialogue-free "Robot Dreams".

The director was not present in Los Angeles to accept the award, and also did not attend a Ghibli press conference in Tokyo where producer Toshio Suzuki spoke instead.

Suzuki said he was "really happy, from the bottom of my heart", but described Miyazaki's less enthusiastic response as "normal, saying the win was good".

Like other Ghibli titles, "The Boy and the Heron" is a visual feast in which mysterious creatures and strange characters cavort through a fantastical world.

After his mother dies in the haunting fire-bombing of Tokyo during World War II, the boy, Mahito, struggles to accept his new life with his father and pregnant stepmother, who goes missing.

Everything changes when Mahito meets a talking heron and embarks on a journey to an alternate universe shared by the living and the dead.

The film's rural setting was "created mostly from my memory", Miyazaki said in a Japanese pamphlet for "The Boy and the Heron", whose original title translates as "How Do You Live?"

Miyazaki, 83, also lived in a big country house during the war.

He has said he did not set out to make an autobiography, but the film's father character "is very much like my own father".

The animator co-founded Studio Ghibli in 1985, building a cult following with his highly imaginative depictions of nature and machines.

Ghibli characters, like cuddly forest spirit Totoro and princess warrior Nausicaa, are now beloved by children and adults worldwide.

"Spirited Away" is about a girl who gets lost in a mystical world where her parents, who she tries to save, are turned into pigs.

- Final film? -

In 2013, Miyazaki said he would no longer make feature-length films, because he could not maintain the hectic intensity of his perfectionist work ethic.

However, in an about-turn four years later, his production company said he was coming out of retirement to make what would be "his final film, considering his age".

That was "The Boy and The Heron", which was released in Japan last July without trailers or other advertising, meaning cinema audiences had little idea of what to expect.

The movie was nonetheless a box office success in Japan and reached number one in North America, where it was promoted as usual.

In Tokyo, Ghibli producer Suzuki said Miyazaki still appeared "energetic" despite the octogenerian's claims.

"He says his eyesight has gone bad and his arms don't work. If you ask me, he's exaggerating," Suzuki laughed.

"It's not going to be easy to make another feature film. Miyazaki has made animation shorts in the past, so I'm now telling him I'd like him to do something like that."

A star-studded cast voiced the film's English dub, featuring Robert Pattinson as the heron alongside Willem Dafoe, Florence Pugh, Christian Bale and Mark Hamill.

In a documentary aired by Japanese public broadcaster NHK in December, Miyazaki was visibly affected by the 2018 death of his Ghibli co-founder Isao Takahata.

The animation master said he had based the character of the granduncle in "The Boy and the Heron" on Takahata, with whom he shared a "love-hate relationship".

"The truth about life isn't shiny, or righteous. It contains everything, including the grotesque," Miyazaki said.

"It's time to create a work by pulling up things hidden deep within myself."