Pure marketing, I guess.
Like all the other weird names we find.
People like the names and pay their price$$$.
And we all have to kinda respect the way it is.
If you can, and like it, pay for it and call what they want you to call.
I believe that those "deep water Japanese zoas" and even "Japanese zoas" can be found in other places and perhaps not in Japan.
Most of them, if not all, are not deep water!
They do have deep zoas down to about 100ft deep in Okinawa, but not the ones they normally sell around.
Sad!
Grandis.