The estimated number of foreign visitors to Japan this year has already surpassed last year's record 19.74 million, topping 20 million in only 10 months, the Japan Tourism Agency said Monday.

The number of visitors in the first nine months of this year was up 24.1 percent from the same period in 2015 to 17.98 million, and the total is estimated to have topped the 20 million line as of Sunday, the agency said.

The rate of increase for the first nine months, however, was half the 47 percent increase logged for the whole of last year, with the yen's appreciation and the Chinese economy's slowdown apparently eating into growth.