A 10-year-old girl complained of a stomachache after drinking a grape juice in which three flies were found, at a McDonald's restaurant in Nara last month, McDonald's Co. (Japan) said Sunday.
The flies were still alive when the girl found them and may have gotten inside the paper cup while the drink was being poured, company officials said.
The shop did not report the incident to local public health officials, but should have done so, it said.
The incident occurred July 17 while the girl was eating at the restaurant with her family. She found the flies at the bottom of the cup after finishing the drink, they said.
She complained of a stomachache and nausea, and was taken to hospital. She was sick again four days later, they said.