Naomi Osaka is an incredible athlete, a champion, and a history maker. But most importantly, she is a role model for others all around the world. The four-time Grand Slam winner has gained significant recognition as an activist and she has most recently become an advocate for mental health awareness.Her remarkable career and work off the court has already made her one of the world's recognised sportspeople and in turn, one of the most marketable. In the space of a few years, Osaka has gone from being a shy figure on the WTA tour, to a leading voice for those who need it most. Her tennis talent and endearing personality is an attractive combination for brands wanting to work with the Japanese star, and Osaka is quite the savvy businesswoman herself. In 2021, the 24-year-old was listed as the world's highest paid female athlete for the third year in a row, and 12th in the world overall after bringing in $60 million (£49m), according to Forbes.An astonishing $55 million (£45m) was from off-the-field earnings, meaning more than 90 percent of Osaka's income was down to her business ventures.

Let's take a look at how Osaka became the most profitable female athlete on the planet.

Tennis success

Osaka was just 20 years old when she made history for her country by becoming the first Japanese player to reach a Grand Slam final.

The infamous 2018 US Open final saw the young star defeat Serena Williams, who was looking for her seventh title at the New York tournament. Osaka triumphed in straight sets, winning a reported $3.8 million (£3.1m) in prize money — her first ever Grand Slam champion pay check.

She then continued her dominance by winning the 2019 Australian Open title, scooping $4.1 million (£3.3m) after beating Petra Kvitová.

Osaka won another US Open and Australian Open title in 2020 and 2021 respectively, winning a combined $5.7 million (£4.6m).

Sponsorships

Osaka is partnered with Nike, who took over from Adidas as her main apparel sponsor in 2019. She is also sponsored by Japanese sporting equipment brand Yonex, who have supplied her with racquets since 2008.

Through her collaboration with Nike, Osaka has her own clothing collection, which debuted last year, featuring a minimalist logo inspired by the Japanese flag.

Osaka joined the likes of Emma Raducanu, Rafael Nadal and LeBron James as part of the Nike athlete family when she signed with the brand.

Brand endorsements

As well as a lucrative apparel sponsorship deal, Osaka has many other brands in her portfolio.

The Japanese star endorses several brands from her home country, including car manufacturer Nissan and airline All Nippon Airways. But the brand relationships close to her roots are not the only ones that contribute to her awe-inspiring status as the world's richest female athlete.

In January 2021, Osaka was announced as the newest face of fashion house Louis Vuitton and appeared in their Spring-Summer campaign. She also signed a brand ambassador deal with Tag Heuer watches in the same month.

Beats by Dre, Mastercard and Panasonic are just a few other household names that Osaka has signed endorsement deals with.

Osaka also has her own Barbie doll designed after her, which was released in 2021.

The figurine sports the famous outfit she wore during the 2020 Australian Open and was created with the hopes of Osaka inspiring young children to be whatever they want to be. Sales of the doll boomed and it was sold out just hours after its initial release.

Another interesting business venture of Osaka's saw her join the video game Fortnite as a playable character. She followed other celebrities including Bruno Mars and Ariana Grande to see themselves become in-game Fortnite skins.

Osaka's character is inspired by her spirit of individuality and pays homage to her Haitian roots as well as giving a nod to her tennis career.

Fortnite is one of the world's most popular video games and it brought in a reported $5.1 billion (£4.1 bn) in revenue in 2020 alone.

As is clear — based on the Forbes breakdown of Osaka's annual income — many athletes' fortunes come mainly from sponsorships and brand deals, as opposed to the performances they put in for their respective sport.

Other business ventures

Osaka is keen to assign her name to other businesses — earlier this week she left management company IMG to start up her own sports agency with longtime agent Stuart Duguid.

The business is said to be "athlete-driven and focused on big picture brand building rather than quick checks with a commission attached."

Osaka also has an investment in women's football team, the North Carolina Courage. The American franchise competes in the NWSL, the highest level of US women's domestic football.

Osaka tweeted about her decision to invest in the club, seeing it as a way to give back to other sporting women who has helped her throughout her career so far.

"Throughout my career I’ve always received so much love from my fellow female athletes so that’s why I am proud to share that I am now a owner of @TheNCCourage," she tweeted alongside images of her wearing a Courage jersey on court.

Highest paid female athlete

Osaka and Serena Williams are the only females in the top 100 Forbes list of highest paid athletes.

The gap between these two women and other high profile female sports stars is staggering. After Williams, her sister Venus was named the next highest earner of 2021 with $11.3 million (£92.m), but still tens of millions behind her fellow tennis icons.

At just 24, Osaka still has a long career ahead of her on the court and her business ventures will no doubt continue to make her one of the world's most marketable athletes. With such an impressive fortune already, who knows the heights the Japanese star will reach?