Princess Aiko, the only child of Crown Prince Naruhito and Crown Princess Masako, turned 13 years old Monday.
The Princess, a first-grader at Gakushuin Girls' Junior High School, developed a fondness for tennis last spring and enjoys playing against her parents on holiday, the Imperial Household Agency said.
The Crown Prince sometimes helps her with her school history and geography assignments, while the Crown Princess, who formerly worked as a diplomat, coaches her English, the agency said.
In July, Princess Aiko went on a three-day school trip to Gunma Prefecture, where she trekked with classmates in the mountains and star-gazed.
At a school festival in November, she served sweets at a booth. She also paid her first visit in July to the Musashino Imperial Mausoleum in Hachioji in the western suburbs of Tokyo, where her great-grandfather Emperor Hirohito, posthumously known as Emperor Showa, and his wife, Empress Nagako, posthumously known as Empress Kojun, are buried.
Later that month, the Princess accompanied her parents to Ise Shrine in Mie Prefecture. It was her first visit there.
