Mari Osaka, the elder sister of four-time grand slam champion Naomi Osaka, said she has retired from playing tennis in her Instagram post on Monday."I am retired from playing tennis. It was a journey which I didn't enjoy ultimately but I'm grateful for all the memories and support I've gained and received over the years from the sport," wrote the 24-year-old."I'm moving on now so you can look forward to new fun projects upcoming in the future."She last played in a women's singles tournament in the United States in January and was ranked 340th in the world as of Monday by the Women's Tennis …READ FULL ARTICLE