New Delhi, Dec. 17 -- Thousands of people flocked to Tokyo's Ueno zoo to have a last glimpse of the popular twin pandas that are set to return to China next month, worried if or when they get to see their replacement in Japan as Tokyo's relations with Beijing sunk.

The Tokyo metropolitan government announced Monday that Xiao Xiao and his sister Lei Lei will return to China in late January and that their last day of public viewing will be Jan. 25.

Their departure will leave Japan without a panda for the first time in more than half a century. Prospects for their replacement are not favorable as ties between the two countries have plunged in recent weeks.

Giant pandas are native to southwestern China and serve as an unofficial national m...