Riajuu is internet slang for somebody who has a good life. It's typically used by otaku and such on message boards like 2chan to refer to people who have girl/boyfriends and are popular with their peers.
by ( ¬‿¬) July 9, 2012
 Get the riajuumug.
Get the riajuumug.  Get the riajuumug.
Get the riajuumug.