"Who set down a law that said that applies here, though? If I didn't know better to accuse you of such a thing, Detective, I would say you're trying to take it into your own hands." There's amusement in those green eyes, which erupts into fully-fledged laughter at Leon's confusion.

"No," He manages to explain, when he calms slightly, "-sama is an honorfic, like Mr or Mrs in western terms."

Not quite the right explaination, but it will be worth it to see the Detective's face next time he goes to Japan and uses it the street.