Beyond my paygrade, I’m afraid. I was a mere English speaking waiter who suffered numerous insults from the Japanese sushi chefs which I did not understand.
However, the head chef liked me enough that at closing time, he let me collect the left-over sushi from the belt, and I took it home for myself, my girlfriend and our cat to enjoy.
Often as much as 2 or 3kg of the stuff, even the cat got tired of eating salmon and tuna sashimi.
Gunkanmaki (lit. ‘battleship roll’) is a unique form of roll, in which the loaf of rice (the shari) is wrapped with a narrow strip of nori forming a kind of cup, with the rice as the base and the walls of the seaweed taller than the rice. It’s the basis for a lot of nigirizushi that feature small or delicate bits which can be better contained in the cup vs being formed on top of the rice loaf. Uni is common, with or without a quail egg, but so are different kinds of fish roe, including salmon, flying fish, or herring. Gunkanmaki are a subset of makimono, which includes tekkamaki (tuna roll), kappamaki (cucumber roll) - which are both forms of hosomaki or ‘thin rolls’ - futomaki (thick roll), uramaki (inside out rolls), and temaki (hand rolls, which are frequently but not always cone-shaped).
If you were being sent home with the leftovers, chances are good that the insults were good-natured.
I had raw scallop sushi in Japan, once, but have never had it in the US. I was at an international event and there wasn’t enough food. (Europeans and Americans eat more than Japanese. Most of the guests were not Japanese. The hotel probably set out enough food for a group of Japanese. It was not enough for this group, and i had come slightly late.) But most of the white people were squeamish about the raw scallops, so there was lots of that, and not much else. That was pretty much my dinner. It was delicious, and I’d love to try it again.