I am reporting my direct experience, bud. I have had senior Japanese executives, in Japanese restaurants, specifically choose dog for me as a delicacy. Which I could't refuse.
But certainly it is a far more common dish in Korea, where I also lived for a while.
I figured it would have to be something pretty rare, I've never met the Japanese person who wanted to eat that, and I know quite a few having lived there on and off a few years. If Mr Shankly is who I think he is, he's lived there much longer than I have.