NAGAOKA, Japan — She has a soft spot for Duffy the Disney Bear and her favorite food is chocolate. She does her homework before dinner but really loves skateboarding, playing video games and bouncing on her trampoline.

If Mahiro Takano sounds like any 9-year-old, think again: The third grader from Niigata, a rice-growing region in Japan, stars in Sia’s latest music video “Alive,” the just-released single from the singer’s upcoming album.

In a backdrop of stark gray, the girl, wearing a white and black wig evocative of Sia’s hairstyle, performs a dazzling routine with quick fists and kicks, and an adorably determined concentration of energy.

Mahiro, a three-time Japan karate champion in her age group, found making a music video was quite fun, and agreed she would do it again, especially if Justin Bieber or Taylor Swift offers.

The video shoot with Sia in a Tokyo suburb took about a week. She made a point to move to match the music, and “look cool,” Mahiro said in an interview at her home, where she was gulping down her dinner of curry and boiled eggs before rushing to karate practice.

“She was nice,” she said calmly of Sia. “She kept saying I was fantastic.”

“Amazing” was the way her thoroughly impressed mother, Masayo Takano, remembers Sia repeatedly praising her daughter.

“I was so excited,” her mother said, letting out a squeal not quite as fierce as the long throaty screams her daughter makes during her karate routines.

Mahiro – whose name means “ten thousand kindness, as well as ten thousand talents” – has a quick sweet smile when she isn’t screaming.

Her kicks, turns and punches in the air are part of “kata” forms that are like choreography in the Japanese defensive martial art of karate. Kata competition is separate from combat matches, which are also part of the sport.

When doing kata, you slip into a focused character, Mahiro says, by imagining “a far more powerful enemy.”

She lost a contest just once, when she was in kindergarten. She wept, she recalls, so painful was it to lose. The trick is to practice as though you are in competition, and compete as though you are in practice, she said.