The number one ask from tourists coming to Japan has always been ease of connectivity to WiFi spots across the city. Primarily to connect to internet and access travel related information tourists had to contend with long subscription processes or sometimes non availability of a carrier contract in Japan, left isolated with no connectivity. Starting December 1, 2014, 143 stations on the Toei line and Tokyo Metro Lines will get a free WiFi Spot called “Japan Connected―free Wi―Fi” which will allow a connection time of over 3 hours. You can connect any number of times in that time period. Hopefully the registration screen will be in English/Chinese/Korean and other major languages, else it defeats the basic purpose of a hassle free connectivity. Hopefully this system matures over the years as we reach Tokyo 2020 Summer Olympics and will offer the best connectivity that one can expect in a 21st century megalopolis.
Please read more about this at http://olympicintokyo.com/blog/how-to-connect-to-free-wifi-on-tokyo-metro-toei-lines/