In the Tokyo subway, you will notice pretty quickly that several public access points Wi-Fi is available, thanks to the many signs like the above picture displayed throughout the halls of the stations.
Ideal to eg share a photo of the Tokyo subway with your friends on Facebook do you say? Nay! These Wi-Fi hotspots are actually reserved for those who already have an Internet connection at home or mobile phone subscription with data, ie the people in Japan.
With the Wi-Fi networks ubiquitous in the subway stations of the city, not surprising that many users (as I do) always have their eyes on the screen of their smartphone.