The Marugame Seimen fast-food “udon” noodle chain apologized on the company's official website after a customer reported finding a frog in its new popular takeout salad udon dish.

“We deeply apologize for causing significant concerns and troubles,” the company said on May 23.

Marugame Seimen received the report from a customer who bought “spicy dandan salad udon” at its restaurant in Isahaya, Nagasaki Prefecture, on May 21, according to the website.

The company said the frog was mixed in at a supplier's vegetable processing factory. It said it will receive guidance from a health care center and conduct inspections at all its vegetable suppliers.

The company said it will suspend sales of some dishes using fresh vegetables from May 23 to 25.

The spicy dandan salad udon is one of five takeout salad udon dishes. Udon, salad and sauce are served in a vertically long container. Customers shake the container to mix the ingredients before eating.

Around 210,000 servings of the shake udon offerings were sold in the first three days since they became available nationwide on May 16, the company said.