Traditional festivals often revolve around shrines and temples and during the summer, expect to see parades through the streets with all those taking part dressed in colorful garb, hoisting heavy portable shrines on their shoulders.
For something beyond the standard matsuri, a trip to the quirky Festival of the Steel Phallus in Kanagawa Prefecture will show you that size matters—at least at this festival in early April. Turn up the heat by attending one of the Fire Festivals—including the blazing Nachi Fire Festival on July 14th in Wakayama Prefecture that climaxes in twelve portable shrines in the shape of the Nachi Falls set alight. Along with festivals of flowers, such as when the baby blue Nemophila blankets the fields of Hitachi Seaside Park in Ibaraki Prefecture in April to mid-May, music festivals are common during the summer with the headline act being Fuji Rock Festival in Niigata Prefecture.
You can also take part in a wide number of events that are scheduled throughout the year. The Tokyo Motor Show is held every autumn and draws huge crowds, as does Tokyo Comic Con. Events showcasing regional food can often be found in Yoyogi Park in Tokyo, and the country's conference centers and forums play host to all kinds of events from tourism forums to presentations of the latest technology.