Hoo boy, this is a really complicated answer that I hope will explain some other things as well.
This is actually a very interesting question that I bet a lot of people wonder about. I learned quite a bit about all of this from what I've been able to research. The interactions between
Up-Front Group Co., Ltd. companies is actually a bit more complicated than most people realize.
I think an explanation of what Up-Front Group actually
is will help. Up-Front Group is often described as a
holding company, which means that it pretty much owns a bunch of other companies. These companies include
Up-Front Agency,
Up-Front Works,
Up-Front Books,
TNX, and
Rakuten Sports Properties. Simply put, it's
really big and has many different concerns in varying industries, from entertainment to food, to real estate, etc. etc. etc. (This explains why Hello! Project always promotes Rakuten Eagles goods.)
Each company under Up-Front Group has a distinct set of operations that it carries out:Up-Front Agency is about "management and promotion" of individual artists/groups. While their company information page lists individual artists, such as Tsunku, SharanQ, Moritaka Chisato, and all the soloists and groups of Hello! Project, there is actually no mention of Hello! Project itself.
Up-Front Works is where Hello! Project
is listed. From what I understand, they actually own the several record labels you may be familiar with, Zetima, Piccolo Town, and Hachama. What I think this means is that the actual music production is done under Up-Front Works, and that "Hello! Project" as a brand is under its responsibility and seems to be its property. TNX is listed under the same general grouping as Up-Front Works.
Up-Front Planning is responsible for concert/event planning and operations. I suppose this would be things like contracting stage builders and light/sound operators for concerts, as well as booking the venues.
Up-Front Music manages the rights, and
Up-Front Books does publishing.
I think the easiest way to explain this is that there's
different companies under Up-Front Group for the "
who" (Up-Front Agency), "
what" (Up-Front Works), and "
how" (Up-Front Planning) of Hello! Project. Just about every facet of Hello! Project's operation is under a different company's jurisdiction, while all being owned by Up-Front Group.
So, the answers to your questions boil down to this:
Hello! Project is owned by Up-Front Works, while the girls' contracts, management, and promotion are under Up-Front Agency. Neither Tsunku nor Up-Front Agency actually owns the brand. In fact, Tsunku is just another artist, in the context of Up-Front Agency. Depending on how it's set up, he might not even own the rights to Hello! Project songs!
As property of Up-Front Group, H!P can not break off from it. If any artists leave and sign somewhere else, the only thing that they retain is their name. No music from H!P or the H!P brand itself is transferred from Up-Front Group's ownership.
I assume this is in regard to Goto Maki's recent return to training, and perhaps signing with a different company. If she does this, she will not be able to do her old songs without Up-Front Music's permission, or have any affiliation with "Hello! Project".
...
Damn that was a lot of text. (tl;dr, anyone?) Most of this information came from
Up-Front Group's List of Companies. If anyone has anything to add or any corrections to this, please feel free to share!
Edit:
Upon closer inspection, Goto Maki's name is still listed on the Up-Front Agency's artist list! This may or may not mean anything. It
could be outdated information that hasn't been updated, but that page also lists the newly added
Fukaya Ai (
wiki page) as a member of Gatas.