It is the main intercity rail terminal in Tokyo, the busiest station in Japan in terms of number of trains per day (over 3,000), and the fifth-busiest in Eastern Japan in terms of passenger throughput. The main station façade on the western side of the station is brick-built, surviving from the time when the station opened in 1914.
Mom and Nancy also got to experience rush hour on the train. Luckily we were able to get Mom a seat in the priority seats and Aunt Nancy got to stand by her in the corner. Those are the best places to be on a crowded train! Other people were being pushed and squished into the train. Just when you think there isn't any more room, another 5 people push their way in. :)