Square Enix's e-STORE has updated with the cover of Volume 4 of the Kingdom Hearts 358/2 Days manga. Volume 4, as we knew before, will be 210 pages long, and available on April 21, 2012 for a price of ¥440 (approximately US$5.47). You can see the cover artwork below.
http://kh13.com/zenphoto/zp-core/i.php?a=manga/358-2-days&i=AqqhP1VCIAAidHB.jpg&h=240&q=75&t=1&wmk=!