http://www.jehovahs-witness.net/watchtower/beliefs/175707/1/10-Years-Japan-losses-5-400-Publishers-and-638-Kingdom-Halls-Why
http://www.jehovahs-witness.net/watchtower/beliefs/175707/2/10-Years-Japan-losses-5-400-Publishers-and-638-Kingdom-Halls-Why
Probably, when "Aum Shinri-kyo" committed a crime, Jehovah's Witnesses in Japan were still growing.
In my opinion, the "incident of Aum Shinri-kyo" and the "decrease of Jehovah's Witnesses" are irrelevant.
In such a case, the Governing Body of JW can emphasize the difference from the other false religions.
Well, in Japan, people began to use the Internet in 1998, and then Jehovah's Witnesses decreased in number in the 21st century.
Probably, many active JWs have realized their/GB's false prophecy (Armageddon will never come).
http://godpresencewithin.web.fc2.com/pages/jw/prophets.html
possible