The pandas, who arrived in Tokyo in 2011, had been receiving medication for age-related high blood pressure, according to the Tokyo metropolitan government. Their departure leaves only two pandas at the Ueno zoo, which has housed the animals since 1972.
"We want them to live peacefully in the environment where they were born and raised," said Yutaka Fukuda, the zoo's director, expressing a mix of sadness and gratitude.
About 2,000 visitors came to bid farewell to the pandas on their final day of public viewing. The animals were then transported early Sunday morning to Narita Airport, where hundreds gathered to see them off.
The pandas' return comes before the expiration of their extended lease agreement, which was set to end in 2026. Japanese and Chinese officials agreed on an early return to ensure proper medical care for the aging animals in their native habitat.