Xiang Xiang lies on a hammock and nibbles on bamboo in a den with her mother, Shin Shin, at Tokyo's Ueno Zoo on June 11. (Video taken by Hiroyuki Yamamoto)

Crowd-pulling Xiang Xiang showed just why she is so popular as she energetically played with a hammock and climbed trees at Tokyo's Ueno Zoo on June 11, the eve of her first birthday.

In fiscal 2017, visitor numbers to the zoo in Taito Ward exceeded 4 million for the first time in six years thanks to Xiang Xiang’s popularity.

The giant panda cub is steadily gaining weight. She tipped the scales at 28.2 kilograms on May 25, making her about a quarter of the weight of her mother, Shin Shin.

Xiang Xiang’s nurturing is also smooth going, a Zoo representative said.

Her main nourishment still comes from Shin Shin’s breast milk, but the weaning process has started, and is expected to be completed by the time she is 18 to 24 months old.

Solid food was introduced in May, when Xiang Xiang was seen nibbling on a chopped-up apple.

The zoo introduced a first-come, first-served system for viewing Xiang Xiang on June 5 to allow more people to see the beloved animal. Still, visitors have to wait in line for a maximum of two and a half hours to see her.

Pandas at the zoo are on loan to the Tokyo metropolitan government from China, and Xiang Xiang is contracted to be given to China when she is 2 years old.

Xiang Xiang is the first panda to be born and raised at Ueno Zoo in 30 years. Yu Yu, another female, was born there in June 1988, and was transferred to Beijing Zoo in November 1992.

Shin Shin also gave birth in 2012, but the cub died in less than a week.