You should avoid the trains in Japan during the intense morning rush hour, typically between 7:30 AM and 9:30 AM, and the evening rush hour from 5:30 PM to 7:30 PM. The morning peak is notoriously crowded, especially on major lines in Tokyo like the Yamanote, Chuo, and Den-en-toshi lines, where "pushers" (oshiya) may still be seen helping passengers into packed cars. The congestion is most extreme around 8:00 AM to 8:30 AM. On Friday nights, the evening rush can extend even later as workers head out for social gatherings, leading to very crowded trains near midnight. If you are traveling with large luggage or small children, it is highly recommended to travel between 10:00 AM and 4:00 PM. Additionally, avoid traveling during major "migration" holidays like Golden Week (late April/early May), Obon (mid-August), and New Year's, when long-distance Shinkansen trains are booked months in advance.