Secret? Not anymore, they aren't.
http://www.japantoday.com/jp/news/389906
Friday, November 10, 2006 at 05:00 EST
ETAJIMA — The only special squad of the Maritime Self-Defense Force has engaged in secret drills to prepare for Japan's possible inspections of North Korea-related ships under a U.N. Security Council resolution following Pyongyang's nuclear test last month, Kyodo News learned Thursday.
The MSDF is carrying out the drills every day at its base in Etajima, a Seto Inland Sea island in Hiroshima Prefecture even though the Japanese government has yet to decide its position on the issue due to legal sensitivities. The government has left various questions unanswered, such as whether it can apply the law on Japan's logistical support for U.S. forces to the situation in the event of defense contingencies in areas surrounding Japan.