@Intrepid,
that is a hoax site so I dont consider that information reliable. A google of "fashion designer" "butt skirt" appears to locate nothing in the first 2 pages, which indicates that this is another wave of the hoax.
It does sound plausible because the young Japanese girls do a really nice mix of slutty and creative. This is something that one can imagine them doing, but I am not convinced that they have.