The older sister of tennis superstar Naomi Osaka has announced her retirement from the sport ... saying she's just not having fun.
24-year-old Mari Osaka made her pro debut in 2011, according to the WTA website. She cracked the WTA's Top 1,000 ranking list in 2012 and made it all the way up to #280 in 2018.
But she never really caught fire on the court -- failing to win a major tournament during her career. She's currently ranked #340 in the world and has only amassed $93,055 in career prize money.