In a bold move, developer Level-5 will force players to complete White Knite Chronicles 1 before they can gain access to the sequel.
According to Japanese site 4Gamer (translated by Andriasang), the second game will only allow you to play the new quest if you have a 'Clear Data' saved from finishing the first game.
Series director Toshiyuki Kusuda confirmed in a recent interview that, without that file, the sequel will force you 'start from the beginning', which basically means play the first game.
The redeeming factor is the inclusion of an enhanced version of White Knight 1 on the same disc as the sequel, with the newer gameplay retrofitted in there, and Kusuda reckons that even those that have already played the original will enjoy playing through it again in its boosted form.
The two versions of White Knight 1 are, however, not compatible online. In case were wondering.
Events in the sequel are set a year after those in the first, and it's out on PS3 in Japan in July. No western release yet.