The Japan tourism explosion stalled in 2019 because of a spat with South Korea qz.com

The drop in South Korean tourists stems from a trade war between Japan and South Korea that makes the US-China trade war look like a minor skirmish.
South Korea was occupied by Japan from 1910 to 1945, and many Koreans were forced to work in factories or into prostitution.
More than 2.9 million people visited Japan from South Korea from August to December of 2018.
Japanese tourism to South Korea also fell, but to a lesser extent.
Visits from Japan to South Korea were only down 14%.