W HEN NAOMI OSAKA won the Australian Open on January 26th and became the world’s top-ranked female tennis player, the inhabitants of her mother’s home town of Nemuro, on Japan’s northernmost island, Hokkaido, celebrated. Congratulatory banners adorned the city hall. Townsfolk flocked to see the display of autographed rackets, clothing and other tennis paraphernalia inside. In interviews her grandfather praised her performance.

That may not seem strange, but in Japan people are typically considered Japanese only if they have two Japanese parents, speak fluent Japanese, look the part and “act Japanese”. Ms Osaka grew up in America and is only hafu (half) Japanese; her father is Haitian. She is more comfortable speaking English than Japanese (or Creole). Her grandfather at first disowned her mother when she told him she was seeing a foreign man.

For some, Japan’s embrace of Ms Osaka is hypocritical: everyone loves a winner. That view seemed to be vindicated when Nissin, a noodle-maker, ran an advert featuring Ms Osaka in which her skin and hair were lightened. (After complaints, the firm withdrew it.) Although Japanese television has long featured mixed-race celebrities, they serve as novelties. Life for non-famous hafu remains tough, with bullying in schools commonplace.

Japan may be becoming more tolerant of those who are different, however. Ms Osaka has been more warmly embraced than past half-Japanese winners of beauty pageants, for instance. “Having someone like Naomi Osaka represent Japan on the international stage would not have been possible a few decades ago,” says Megumi Nishikura, a hafu herself and a co-director of the film “Hafu”.

To some degree it is a question of numbers: 3.4% of married Japanese have a foreign spouse and three times more foreigners live and work in the country today than a decade ago. Yet the fact that the Nissin advert made it into production is “a clear indicator of the challenges that remain”, says Ms Nishikura. Since Japan does not technically allow dual citizenship for those over 22, Ms Osaka will in theory have to choose in October whether she feels Japanese enough to renounce her American citizenship and continue to play as Japanese.