Japanese tennis sensation Naomi Osaka not only hit the cash jackpot with her historic U.S. Open victory -- she struck a blow for racial equality, according to a former Miss Japan.

Following her 6-2, 6-4 victory over childhood idol Serena Williams in New York earlier this month, Osaka is set to become a global marketing force as sponsors prepare to break the bank to sign the 20-year-old.

But Priyanka Yoshikawa, who two years ago was crowned Miss Japan, believes Osaka can also help break down cultural barriers in a country where multi-racial children make up just two percent of those born annually.

"Naomi is definitely a role model," the half-Indian beauty queen told AFP. "Japan should be proud of her -- she can definitely break down walls, she will have a big impact."

Osaka, who has a Japanese mother, a Haitian father and was raised in the United States, is set to shine a light on what it means to be Japanese, predicts Yoshikawa.

"The way she speaks, and her humbleness, are so Japanese," said the 24-year-old. "Japan puts all haafu in the same bucket," added Yoshikawa, referring to the Japanese for "half" -- a word to describe mixed race. "Whether you're part Russian, American or African, you're still categorised as haafu in Japan."

Yoshikawa's Bollywood looks swept her to Miss Japan victory a year after Ariana Miyamoto faced an ugly backlash in 2015 for becoming the first black woman to represent the country.

Critics took to social media complaining that Miss Universe Japan should have been won by a "pure" Japanese.

Unlike Yoshikawa and Miyamoto, Osaka speaks hardly any Japanese after moving to Florida with her family as a toddler.

"It's not about language," insists the Tokyo-born Yoshikawa, who was bullied because of her skin color as a child. "Why does that bother people? It's just because she has darker skin and is mixed race. People still ask me if I eat curry every day or if I can use chopsticks! But she's what she thinks she is. If you think you're Japanese, you're Japanese."