The little Sega logo on the top right makes me think it's a Sega ad making fun of people who used to think games weren't for homes. Maybe they were copying the Pepsi/iTunes commercial and glorifying the criminals.Gen KanaiFunny keitai photo
(the caption on the sticker can be loosely) translated as:
"Games should be played only in game arcades."
(Which is a riff on the fact that it is rude to talk on the mobile phone on the train here in Japan.)
I wonder if the expected social norm of not talking on the phone in trains in Japan will change. If people learned that shouting into your phone doesn't really help and talked in a normal voice that might help. I don't see how that would be any different than two people talking to each other face to face from a noise pollution perspective. (I can see a bunch of other arguments here about why it's not the same thing as face to face, but I'm not going to go there.)
The fact that you have to have a sign forbidding it must mean that there is a gap between some people's behavior and hoped for behavior by a particular group of people with access to the authorities.
Anyway, I'm all for talking on the phone in trains.