Comment Actually, not the Subway (Score 1) 61
I was on this train last night, actually, at it was a pretty wild experience once you realized the entire train was outfitted in Star Wars ads. The lightsabers are definitely a nice touch. That said, trains occasionally get the all-car treatment, and I remember one Yamanote line train being made up in Meiji Chocolate-bar wrap (as part of an anniversary event, being used as a call back to the lines original brown colour), and another time when a train was made out for a breath mint add where all the handlebars were shaped like mint packets!
One note, however, is that it is actually a Sobu Line Local (JR) train, not the subway.
Meiji Yamanote Train: http://www.japantrends.com/ride-the-meiji-chocolate-choo-choo-yamanote/