Gao Yuan looks at photos he's taken. [Photo/VCG]

As for the unclaimed photos, Gao said Weibo really worked. Last September, a Henan peasant contacted him on social media. The man said he was 18 when he and his father had their picture taken in Tian'anmen Square, but they hadn't received their photo.

Gao then sent him several pictures based on the man's description. It was unbelievable that one of the photos showed the portrait of the man and his father in the 1990s.

"Media reports about me will help find the photos' owners, too," Gao said. "If I can find these people, what I want to do most is take another photo for them. It's also like a ritual, my ritual."