Baye McNeil, an African-American columnist who writes for the Japan Times about the black experience in Japan and who has lived in the country for 14 years, said the celebration of Ms. Osaka presented a racially progressive view that did not align with a messier reality.

“This country prides itself on being homogeneous,” Mr. McNeil said. He said that to have a woman of mixed cultural heritage rise in the spotlight placed many Japanese “in an awkward position of sending a message to the world that they’re in a place that everyone knows they’re not.”

But Japan, however slowly, may be changing. The year after Ms. Miyamoto won the beauty contest, another mixed-race woman, Priyanka Yoshikawa, took the crown.

Megumi Nishikura, co-director of the documentary “Hafu: The Mixed-Race Experience in Japan,” said, “Anybody who is able to represent Japan in a public way who is ‘hafu’ will open Japanese minds and hearts to being more accepting.”

“We live in a world where people have a limited view on nationality and race and ethnicity and say that you can only be one, you can’t be more,” added Ms. Nishikura, who was raised in Japan by a Japanese father and Irish-American mother and who now lives in New York. “I think Naomi Osaka really presents a very interesting challenge for people who are still attached to these antiquated ideas that you can only be one.”

In Tokyo on Sunday, there were signs those antiquated ideas might be shifting. “I think the definition of what is Japanese is becoming vague,” said Masako Mikami, 52, who works at a gaming software company in the city. “I think Japanese society is changing to become more generous. Naomi Osaka is one of the next generation of Japanese people.”