Princess Kako, the younger daughter of Crown Prince and Princess Akishino, attended the opening ceremony on Saturday of a two-day event marking the 50th anniversary of diplomatic ties between Japan and Vietnam.

Her aides say she spoke with four Vietnamese students studying in Japan before the ceremony started at Tokyo's Yoyogi Park.

A musical performance on the bamboo instrument, the t'rung, followed a speech by former Japanese Prime Minister Fukuda Yasuo, who serves as the event's senior advisor.

Princess Kako applauded at the conclusion of the ceremony as a suspended paper ball was pulled open to release a colorful stream of ribbons.