Japanese trailblazer Osaka happy to share spotlight with 'big kid' Kei

Trailblazer: Naomi Osaka celebrates her win against Lesia Tsurenko which put her into the US Open semi-finals

Japanese Grand Slam trailblazer Naomi Osaka said Wednesday that she's happy to share the US Open spotlight with Kei Nishikori, describing her compatriot as "a big kid" in a show of openness which is rapidly transforming the 20-year-old into the sport's new poster girl.

Osaka became the first Japanese woman in 22 years to reach the semi-finals of a Grand Slam when she defeated Lesia Tsurenko 6-1, 6-1 at Flushing Meadows.

However, she insisted that despite her growing profile -- and evidence to the contrary -- it is Nishikori who is the main driver of Japanese media attention.

"He's probably one of the nicest people I have ever met. We recently started talking. I think it's because I was too shy to talk to him before this tournament," said Osaka of Nishikori who was runner-up in New York in 2014.

"But then I started talking to him, and I think he was surprised about me talking to him. So, yeah, he's really cool."

Nishikori and Osaka have made history this week by becoming the first Japanese players to make the last-eight of the same Slam since Shuzo Matsuoka and Kimiko Date at Wimbledon in 1995.

Date was the last woman from the country to get to the semi-finals of a major at the All England Club the following year before Osaka was even born.

Osaka has already become a hit with media and fans at the US Open.

On her on-court interview after beating Tsurenko on Wednesday, she told the crowd that she was "freaked out" over making the semi-finals.

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She had their sympathy when she revealed that she had become the butt of ridicule for breaking down in tears after her quarter-final win before having them in fits of laughter by claiming "I like sweating".

US tennis legend Billie Jean King took to Twitter to get behind the WTA's newest star.

"@Naomi_Osaka_ I'm terribly sorry you were teased for crying following your @usopen victory. Never, ever be afraid to be your authentic self. #champion," tweeted King.

Osaka's coach Sascha Bajin, who famously once worked with Serena Williams, said her openness can be a problem.

"I want her to not say certain things and she actually does say it. She's very open with you. She threw me under the bus in a lot of other conferences," joked Bajin.

To prove his point, Osaka elaborated Wednesday on her relationship with Nishikori.

"I don't know if I'm going to get in trouble if I say this," she said in preface.

"I just think he's, like, a really big kid. He plays games and stuff, too. I think we're pretty similar in that sense. Overall, he's just really nice and positive and bubbly and stuff."

Osaka, who has a Haitian father and Japanese mother, has spent all of her adult life in the United States, in New York and Florida, with just a few years of her childhood in Japan.

She responds to media questions from the Japanese press in English with a smattering of a few Japanese words.

She describes going to Japan as "a super-awesome extended vacation that I don't want to leave".

When Bajin first came across Osaka he thought she was "bit more of a diva because she didn't talk much".

"She doesn't really look at someone's eyes, but that's just because she was always so shy. She would just keep her head down a little bit, which is cute now. I feel bad for prejudging."

He added: "I think everybody in this room and on this planet can learn a lot from that girl in order to maintain that innocence."