According to their website, JManga has concluded its retail and viewing services. All existing accounts and private information will be deleted without further notification.
A service termination schedule was posted:
a.) JManga Point Distribution and Sales Termination: March 13th 2013 at 11:59pm (US Pacific Time)
b.) Digital Manga Purchasing Service Termination: March 26th at 11:59pm (US Pacific Time)
c.) Manga Viewing Service Termination: May 30th at 11:59pm (US Pacific Time)
JManga Inc., was established on December 27th 2010 to support the 39 prominent publishers that make up the Digital Comic Association. JManga.com was formed with the goal of making Japan's manga as accessible as possible to readers worldwide in a legal environment beneficial to both the readers and the publishers. With digital comic retail, manga promotion, and development of other manga related services as our main business areas, JManga, together with manga publishers around the world, strives for the growth, progression, and expansion of the worldwide manga market.