This is the main calendar for all events listed on this website (including seasonal nature festivals such as the cherry blossoms), exhibitions, firework festivals, and technology and trade shows. The majority of the events on the calendar are free, but in cases where an entrance fee is required the details will be given at the end. The dedicated events calendar for Tokyo can be found here.
All dates for events and festivals listed in this events calendar are taken from the official websites. In the case of some recurring events and festivals, future listings are based on the scheduling of prior year events because dates are not usually officially announced by the organisers until one month before. I make efforts to regularly check the official websites, but if you do notice an error in the scheduling or details please let me know and I will correct as soon as possible.