IU is gearing up for her Korean comeback as well as her Japanese debut. These are the known dates for the releases.
Jan 2012: First official showcase in Tokyo
Feb 2012: Release of first Japanese debut single
The tracklist for her Korean album isn’t out yet, but it’s called Last Fantasy, so I’ll venture to guess that the title track is called Last Fantasy, which will also be included on the Japanese pre-debut album I□U. That would mean that the only new material (assuming you own all the Korean stuff) on the Japanese pre-debut album is the documentary DVD.