One of the themes of being an American expat in Japan is discovering how much the country has taken various cues from Britain. It starts out with cars, getting used to "strange" car-related words like bonnet (the hood of a car), tank lorry (a tanker truck), or Toyota Super Saloon, a car with a name that makes Americans think of the Old West until they learn that saloon is just the British word for sedan. Americans might make a visit to the bathroom or the restroom, but in England (I'm told) they are more likely to use the word "toilet," which is the same in Japan -- and I've gotten some funny looks in stores in the States asking the cashier where the "toilet" was. Then there are clothing-related words that the Japanese imported from Britain, like a sweatshirt or sweater being called a "jumper," and of course the infamous word "pants," which refers to trousers, jeans or slacks in the U.S. but underwear in Britain and Japan. This explains fandom's obsession with the word pantsu.
The legendary flying pantsu from Heaven's Lost Property, if you've not seen it.