This is my walk through Tokyo station from the Yamanote line platform to the Keiyo line platform. Shinjuku and Ikebukuro are the two largest stations in Japan, I don't know if Tokyo is third, but its pretty big. I always take the Keiyo line to go back home because it stops in Soga and most importantly, I can always get seat. If you've ever stood on the Chuo Sobu line from Akihabara to Chiba you know what I'm talking about.