The Soryu Class diesel-electric submarines are being built by Mitsubishi Heavy Industries and Kawasaki Shipbuilding Corporation for the Japan Maritime Self-Defense Force (JMSDF). Ten Soryu Class submarines are planned for the JMSDF. The class is an improved version of the Oyashio Class submarine.
According to Forecast International, the U.S. Navy Surface Ship Torpedo Defense (SSTD) program is developing and fielding six prototype Torpedo Warning System/Countermeasure Anti-Torpedo (TWS/CAT) Engineering Design Model (EDM) systems on CVN ships.
The keel for the first submarine in the class, Soryu (SS-501), was laid down in March 2005. It was launched in December 2007 and commissioned in March 2009. Unryu (SS-502) was laid down in March 2006, launched in October 2008 and commissioned in March 2010. Hakuryu (SS-503) was laid down in February 2007 and launched in October 2009 for commissioning in March 2011. The fourth and fifth submarines under construction are scheduled to be commissioned in 2012 and 2013 respectively.
SS-506 Kokuryu was laid down 21 January 201, launched 31 October 2013 and commissioned 9 March 2015.
The 6th Soryu-class SSK, SS-506 Kokuryu, (meaning Black Dragon) of the Japan Maritime Self-Defense Force.