If you get on a train betweeen 7:00 AM and 10:00 AM in the morning you will most likely find yourself stuffed inside with more people than you can count. I felt like a sardine shoved into a can the first time I tried to ride at rush hour!
Trains are very connected to Japanese culture! When Japan became an industrialized country in the early 1900s, Emperor Meiji was given a train by the United States, because the U.S. wanted to establish a trading relationship with Japan. He loved it so much, and decided he wanted to focus on train systems for Japan. The Ginza Line, one of the most popular train lines in Tokyo, was started around that same time and it still runs today! That's over 100 years old! The train system is a symbol of Japan's rapid industrialization.