There are many holidays in the fall. The second Monday in October is a Japanese national holiday called taiiku-no-hi (Health and Sports Day). Various sports events take place on this day. In Japan, sports festivals called undou-kai are often held in Japanese schools and towns during the autumn.
November 3 is a national holiday called bunkano-hi (Culture Day). There are many events held around the country to celebrate art and tradition on this day. November 15 is called shichi-go-san which is a traditional Japanese festival for children of seven, five, and three years old. This is not a national holiday but is an important family event. Families with children of the ages visit shrines to pray for their healthy growth. Children put on nice clothes, such as kimonos, dresses, and suits. They buy chitose-ame (long stick candies), which represents longevity. You might see many dressed-up children at shrines around the country in November.
Many autumn festivals are held throughout the country to give thanks for the harvest. You might be able to see some Shinto rituals held at various shrines. Also, it's fun to visit many food vendors which sell local speciality food, crafts, charms, and other regional items in such festivals.