This is not specifically related to Kumamoto but, of course, people in Kumamoto are not exempt. If you’re feeling like this is deja vu all over again, you’re right (different drug; similar issue):

https://www.facebook.com/Kumamotoi/posts/794793347260766

Quotes:

“Julie Hamp, named Toyota’s first female managing officer in April, faces drug-smuggling charges after having oxycodone pills sent to her from the United States . . .”

“The U.S. Embassy in Tokyo warns its citizens to check before mailing or carrying medication to Japan, or face arrest and detention.”

http://www.japantimes.co.jp/news/2015/06/19/national/crime-legal/strict-drug-laws-put-expats-risk-execs-arrest-shows/