The Four Seasons Marunouchi provides a platform Bell Boy service for guest pick up/drop offs (with a 1000 Yen Charge). If you are interested, I am sure the GH can arrange something similar for guests arriving via the Subway/Train? Although the distance from FS to Tokyo Station is walkable and I have no idea which is the nearest Subway station to GH......

I agree with other posters, just go for a Taxi after the NEX...it will keep you sanity. I did this and found it to be the most hassle free. (I'd recommend everyone to skip the Limousine Bus.....it's a L-O-N-G and enduring ride, especially in afternoon traffic after arrivel......)