Breakdancer, 40, on cusp of fulfilling Olympic dream
But the former kindergarten teacher won a qualifier in Shanghai and is in pole position for a prized spot at the Paris Olympics.
A repeat performance in Budapest next month would send her to this summer's Games as one of the favourites for gold.
Breakdancing, or "breaking" as the sport is officially called, will make its Olympic debut in the French capital.
"I'm old but I don't feel too much old," Fukushima told AFP in English after her victory in China at the weekend.
Fukushima has long been a trailblazer for "B-girls" -- women breakdancers -- in what has traditionally been a male-dominated scene.
In 2017 she became the first woman to compete at the Red Bull BC One World Finals.
She has since won at the 2021 WDSF World Breaking Championship in Paris, where the competition was split into men and women categories.
She also took bronze at the 2022 World Games and 2023 Asian Games in Hangzhou, China.
Fukushima first dabbled in breakdancing as a shy 21-year-old student.
"In my generation it was kind of normal to start when we're in university," she said in Shanghai, where she topped the B-girl competition.
"But these days most of the people start when they're kids."
Fukushima never thought she would have a chance to compete in the Olympics.
Given her age, it could be her first and last shot at it.
"It's a new thing for us, for the Olympics, so I'm really happy to be in this process," she said.
Japan has long been a breakdancing powerhouse, with three Japanese B-girls and one B-boy making it onto the podium in Shanghai on Sunday.
"All the young people are very strong," Fukushima said of her teammates.
"It's not only winning, we enjoy this moment."
Sport and culture
For years Fukushima balanced her day job as a teacher with her role as a member of a dance crew based in Kyoto.
She has cut back on her teaching duties in recent months, telling AFP that she is now "more focused on dancing".
But she carves out time to give dance classes to young children, whom she hopes will bring the fledgling sport to greater heights.
"Everywhere I go I see many kids interested in breaking... and for us it's really happy."
On the sidelines of the Shanghai qualifier, dozens of children practised breakdancing moves at a public workshop intended to popularise the sport, while the Japanese team warmed up nearby.
"Hopefully we get more people to get in touch with our culture," Fukushima said.
And while other longtime dancers have debated whether inclusion in the Olympics could compromise the freewheeling, rebellious spirit of breakdancing, Fukushima said she doesn't believe the culture of breakdancing will change.
"We have a sport and a culture... I think we're gonna grow both together," she said.