Hokkaido Butter Baked Potato Kit Kat. A product of Japan. Purchased from Jappy11 on EBay.
There's no English on the wrapper, so I guessed the flavor before checking the auction's photo, and guessed wrong. I'd also ordered a buttered roasted corn flavor and thought it was that one. I didn't recognize any potato flavor from it, just the butter. I'll see how corny the roasted corn flavor is when I get to it. It's still very good.