Japan?s Princess Aiko turned four yesterday as debate swirled over a proposal to change the imperial succession law to enable her to become the first female to ascend the Chrysanthemum Throne in centuries. Aiko, who has shed her baby fat but is still the spitting image of her father, Crown Prince Naruhito, clutched a stuffed animal and waved from a limousine on her way to visit her grandparents, Emperor Akihito and Empress Michiko. Photos released by the Imperial Household Agency, which orchestrates the royal family?s public appearances, showed Aiko in a round of activities from finger-painting and ?rhythmic dancing? to playing with clay and gathering mandarin oranges with her parents in their palace garden.

The royal birthday comes just one week after advisers to Prime Minister Junichiro Koizumi recommended that women be given equal rights to inherit the throne, urging a break with ancient tradition to avoid a looming succession crisis. No boys have been born into the royal family in four decades, and debate over whether to revise the law intensified after Crown Princess Masako gave birth to Aiko, her first and only child, after nearly eight years of marriage to the crown prince. Most Japanese back the proposed change, which would make Aiko second in line to the throne after her father. But traditionalists want to preserve an imperial male line they believe stretches back more than 2,000 years.

Japan has had eight reigning empresses but none passed the throne to their own children. ?Changing the rules of succession also means changing the way Japan ought to be, and ultimately changing Japanese history, for that matter,? wrote Hideki Nagane, an author who has been arguing online against reforming the succession law. Masako, a vibrant career diplomat before her marriage, has been largely out of the public view for the past two years due to a mental disorder caused by the stress of adapting to the strictures of court life, including pressure to produce an heir. She may well have mixed feelings about prospects that her daughter will become Japan?s first reigning empress since the 18th century, assuming a role that is devoid of political power but rich in symbolism and ritual. If Aiko becomes heir to the throne, she will soon have to begin the complex training that goes with the position.

Linda SIEG