I've explained this to a few people lately, so maybe a proper public explanation is in order!
Late last year, GACKT started the process of changing his management and staff company from GORDIE Entertainment to a new company. That process completed a couple of months ago, so there's a lot of new company names floating around at the moment (Avex remains the record company).
The new parent company is
第一興商 (Daiichikosho). They own the Big Echo karaoke chain (nothing to do with geckos,
khysmet!), as well as the DAM karaoke system and they bought Nippon Crown (GACKT's old record label) back in 2001/2. They are a huge company.
A sub-company of Daiichikosho is Hoshi Create. This is the actual company that GACKT is under. They're the name on his OHP, the watermark on the Underland downloads and the copyright on the MGGs.
As GACKT is probably a time consuming and resource heavy undertaking (hahahahaha), Hoshi Create created a specific team/office to deal with him. This is called GACKT PROJECT, and is the name on the tour tickets, etc.
So, you may see three different names associated with him, but they're all basically the same thing.
第一興商 (Daiichikosho) - parent company
Hoshi Create - sub-company
GACKT PROJECT - the specific GACKT team
They cover his management and DEARS.
That is all pretty much public record if you're willing to dig around on some Japanese sites.
This next paragraph is, however, pure speculation on my part. None of it is backed up or referenced anywhere so don't quote it as fact, please XD
I wonder if the change in companies is the reason for the Platinum Box delay (the second one) and the lack of a MOON SAGA DVD yet. The Platinum Boxes are not Avex releases - they're released under DEARS - so I wonder if there is any legal things and copyright transfers that have to happen before it can be released. Also, I believe that GORDIE had a stake in MOON SAGA, so that could explain why in January the DVD was being edited but it's now May and we still haven't heard anything.