How to get from NEX line to Yamanate line or Marunouchi line

Hi there!

The simplest way will be to hop on the Marunouchi line at Tokyo and then change at Ginza for the Hibiya line. At least this way you're in the subway system from Tokyo all the way to your destination.

The NE'X is a JR train, so changing between other JR trains will be fairly easy at Tokyo. As an alternative, if you don't like changing trains in busy stations, how about using the JR Yamanote all the way to Ebisu and then changing there to 1 hop on the Hibiya line to Hiro-o? (Or maybe even walking form Ebisu?)

For reference, this map of Tokyo station may help.

Hope this helps!