It's like they took the meat off the bone, ground it up and seasoned it, and then put it back on the bone (i.e. they deboned and then re-boned the meat). It seems like a lot of work.
When I first saw the picture, I thought it was some sort of weird brown banana for a second. From the description, it seems like the idea is for the bone to serve as a handle to eat the sausage the same way you'd eat a rib.
I don't know when these first appeared on the Pizza Hut Japan menu but they don't appear to be new.
