How we cite our quotes: (Part.Chapter.Paragraph)
Quote #1
"What lies there," he wondered aloud, "across the sea?"
"Nothing you want to know about," Denzo said, hurrying to hoist the sail. "Barbarians live there. Demons with hairy faces, big noses, and blue eyes!" (1.1.3-4)
This is our first introduction to what "barbarians" (i.e. white people) are supposed to be like. Scary, huh?
Quote #2
"The law says, 'Any person who leaves the country and later returns will be put to death.'"
They brooded on this in silence.
Finally, Manjiro said, "But why?"
"Because, if we were to encounter any of the foreign devils, we would be poisoned by them." (1.2.40-43)
Goemon and Manjiro are commiserating about how they might not be able to return to Japan. Why? Because Japan in the late 19th century is completely into isolationism, which basically means Japan wants nothing to do with any other country in this book. "Foreign devils" is some pretty strong language, though—it seems personal instead of political.
Quote #3
"Maybe not our bodies, but they will poison our minds with their way of thinking. That's why no fishermen are allowed to go very far from the coast—they say 'contamination lies beyond the reach of the tides.' The barbarians would fill our heads with wrong thoughts!" (1.2.45)
So this is what's wrong with all those "barbarians." But seriously, fear of "wrong thoughts" sounds a lot like an overprotective parent.