I know Jean and Camille did that whole pretend to be in a relationship thing but goddamn they're super cute together. It seems Jean is becoming aware of some kind of feelings for Camille but it's the definition of a slow burn.
Uh . . . which Nobu chapter? and why "gun"? How does that work?
"If you let your guard down, you'll get 'shot'" does not explain anything!
OK, according to the oysterencyclopedia.com
Great Gun oysters derive their name from Great Gun Beach. This beach is located directly south of the farm along the Fire Island National Seashore. This name choice emphasizes the oyster’s strong connection to their Moriches Bay environment.
There is no other connection I can find in a casual search to connect oysters and guns. But this name, being based on a particular American location, would have no meaning in another world. Or in Japan, for that matter.