YOKOHAMA, Japan (AP) Naomi Osaka has been announced as the ''brand ambassador'' for a major Japanese car maker.

Osaka has been the main subject on talk shows and in newspapers since she defeated Serena Williams last weekend to win the U.S. Open title. She is the first Japanese player to win a Grand Slam singles title.

Osaka appeared Thursday at Nissan's headquarters, which was mobbed with media curious to see the new champion who was born in Japan to a Japanese mother and a Haitian father, but left Japan at 3 to live in the United States.

She also made an earlier appearance at a five-star Yokohama hotel.

Her mixed-race background - and those of many Japanese athletes - has raised the question about what it means to be Japanese.