Japan's Princess Aiko, 4, starts kindergarten

TOKYO (Reuters) - Clutching her mother's hand and smiling briefly at TV cameras, Japan's 4-year-old Princess Aiko -- the only child of the direct heir to the throne -- started her first day of kindergarten on Tuesday. 

Aiko, wearing a uniform with a pleated blue skirt, matching jacket and hat with a downturned brim, arrived at the elite Gakushuin Kindergarten in Tokyo with her parents, Crown Prince Naruhito and Crown Princess Masako. 

Shortly before going into the school to join about 50 children for an entrance ceremony, Aiko dropped her father's hand and latched on to her mother. 

Japan's Princess Aiko, the only child of Crown Prince Naruhito and Crown Princess Masako, arrives at the Gakushuin Kindergarten to attend the entrance ceremony in Tokyo 11 April 2006. (REUTERS/Kazuhiro Nogi)

Masako, who has been suffering from a stress-related illness for more than two years due partly to pressure to produce a male heir to the ancient monarchy, also smiled and waved. 

Plans to revise Japan's male-only imperial succession law to clear the way for Aiko to inherit the throne were shelved after news in February that the wife of the emperor's younger son was pregnant with a third child, raising hopes of a male heir. 

No royal boys have been born since 1965, and advisers to Prime Minister Junichiro Koizumi had proposed last year that the law be changed to let women and their children inherit the throne. 

But Koizumi decided not to submit the legislation, which conservative lawmakers staunchly oppose, to parliament after news of the royal pregnancy.