TOKYO (Reuters) - The number of foreign visitors to Japan plunged 87% in 2020 to a 22-year low as the country mostly closed its borders in response to the COVID-19 pandemic, Japan National Tourism Organization data showed on Wednesday. The number of foreign arrivals, which include tourism and business arrivals, fell to about 4.1 million last year from 31.9 million in 2019. It was the lowest annual figure since 1998.