The Japanese antidumping law neither works nor is it practiced. Until very recently, it has been a case of managed economy, with extensive government-business interaction obviating the need to use antidumping laws. While some legislation has been on the books, there's never been an action filed under the available legal framework for antidumping actions.
Antidumping Law in Japan,
Mich. J. Int'l L.
Available at: https://repository.law.umich.edu/mjil/vol1/iss1/14