They use the word "jacket" in Japan to mean the keepcase art. According to the description, they're like an early-bird bonus. They aren't actually pictured anywhere yet though.
Just received my copy today...extremely disappointed to find out that Amazon JP only sent me one slipbox jacket, even though the listing (and extra price) was for all three jackets (that seemed to be my impression...guess I was wrong).
Packaging was a piece of @%^&...the thinnest envelope (with no padding) with a cardboard insert. I'm surprised it arrived in the condition that it did. There was a single pressure crease/wrinkle on the front cover by Chiron's nose. Hard to capture it with the plastic seal I kept on and my phone's poor picture quality. Item came with a bonus picture (see last image).
Going to return my copy since it came out to be $54 USD and wasn't any different than this listing.