McDonald's Co. (Japan) said Wednesday it overcharged customers on over 100,000 purchases of two of its menu items that went on sale Monday at discount prices.

The fast food chain said on its website it will refund the extra cost to customers who bought items including four-piece sets of Tofu Shinjo Nuggets, or fried balls of pureed fish meat, tofu and vegetables, and two-piece McWings fried chicken sets, in addition to the same items in sets containing more pieces.

Both items went on sale at ¥120, about half their list prices of ¥249 and ¥215, respectively. However, the company found out Tuesday its McDonald's hamburger restaurants had mistakenly sold them at ¥150 or even at their list prices, according to NHK.

The company estimates the extra charges may total ¥730,000, and the restaurants that made the mistake total about 2,500. It attributes the debacle to inadequate communication on pricing, NHK said.

The refund will be made to customers who made the purchases from 5 a.m. Monday to 4:59 a.m. Thursday and who present receipts of the purchases, the company's webside said.