Treasure recently stated during an interview with
Eurogamer that they are in fact working on a true sequel to
Guardian Heroes. The company has been planning the game for a while, but when it was pitched to Sega, it was decided that the IP needed re-introduced to the gaming world before a sequel was announced. That is the reason that an HD version of the original Guardian Heroes is coming to the Xbox Live Arcade next month.
Hopefully the new version of the Satrun classic will get the love and respect it deserves when it launches and Sega and Treasure can move forward with the production of the sequel. Do yourself a favor and check out the game when it launches in a few short weeks... it is a fantastic experience that should not be missed.