The above ad announces the debut of a new mascara from Lancome that uses a vibrating applicator brush. The poster is made from electronic paper—a technology that allows paper to be written and rewritten repeatedly. So what you're looking at is essentially a paper poster hanging from the ceiling of a subway train in which the image changes.

Similarly some train stations are now equipped with poster banks for electronic paper ads that can refresh with new images at specific intervals. If you're an advertiser and you rent the space, you can replace the ad whenever you want while sitting right at your office desk, since the wall frames are connected to PHS phone networks that tap into the internet.

 "Japan is one step closer to making every surface an ad" »