But there are up to 40 million journeys across all rail systems in Tokyo each day. More than 30 million people live in the Greater Tokyo area, and more than 8.1 million of them use trains every day.

' Tokyo Doc ' is a browser game that uses Tokyo's subway system as a quiz. The game involves a 3x3 grid with three conditions in each row and column, such as 'Marunouchi Line' or 'contains two or more ...