Well, after that trip, I was surfing the web and found that their Chocoppe was quite popular.
Koppe pan is actually a made-up Japanese word apparently taken from "coupe" in French and "pao" in Portuguese.
This particular koppe pan was like french bread with a slather of dark sweet chocolate.
Isuzu bakery, theirs is called chocolate france. (The Japanese sometimes call baguette "france pan".)
Köln's version is delicious, I loved the chewiness of the bread and the chocolate has just the right amount of sweetness...perfect snack with coffee.