Naomi Osaka is the toast of Japan after winning the Australian Open last weekend and becoming the first Japanese player to be ranked No. 1 in the world. She faces an awkward deadline, however. Japan's Nationality Law requires Japanese who have additional citizenships to choose just one when they turn 22. Osaka, who holds both U.S. and Japanese passports, reaches that age later this year. Though Japan has rarely enforced the rule, Osaka's celebrity poses a challenge to a country historically obsessed with national and ethnic identity. She most likely won't be able to dodge the decision.
Her dilemma is hardly unique in Asia. While many other parts of the world have been opening up to the benefits of dual-nationality, Asia's wealthiest and most populous economies — including Singapore and China — have stubbornly resisted doing the same. It may be time to rethink that opposition. Countries that welcome dual citizens are magnets for globalized talent and capital — two things Asia's aging societies are increasingly going to need if they want to remain vibrant and growing.
Historically, citizenship was viewed as a kind of exclusive relationship, permanently committing the individual to the nation. In cases of international marriage and children, citizenship was typically assigned on the basis of the husband's and father's citizenship. This could have ugly consequences: As recently as the 20th century, American women who married Chinese, Filipino or Japanese nationals automatically forfeited their U.S. citizenship in favor of their husband's. As of 1960, more than half of the world's countries stripped nationality from anyone who voluntarily adopted the citizenship of another nation.