So I was thinking "Well, that's a moderately funny gag . . . ah, joke . . . how creative to invent such a silly--" then I saw the credits. Oh, Japan. LMAO.
^Yeah but they are probably mostly saying that because of the credit page- and that probably being what inspired the manga anyways. THAT picture is for sure out of Japan not China- so it is JAPAN we owe for the existance of the bread gag lol.
I feel that, historically, this was supposed to be a method of keeping the bread in one's mouth for "high school girl with bread in mouth" cosplay. Then someone actually into BDSM saw it and realized what had been created. Or something.