Japan is well-known for its polite populace, but that doesn't mean everyone follows the rules. Nowhere is this more apparent than on the country's crowded public transport networks, where people frequently listen to loud music, do their makeup, and take up space on the priority seats.
To combat these breaches of the peace, in 2008 the Tokyo Metro commissioned a series of 36 posters (collected here in full by Gakuranman) that set out to educate people on the right way to behave. Bunpei Yorifuji's simple line art and even simpler messages became instantly recognizable on Tokyo's subways, and while we can't say they entirely eliminated bad behavior, they did make riding the trains more amusing for a while. If you want a crash course in Japanese subway etiquette, we'd recommend seeing the full set.