This annual event in 2021 was canceled due to COVID-19
Known as one of the three largest annual festivals established in the Edo period (1603-1868), Fukagawa Hachiman Matsuri is such a popular traditional festival where 300,000 visitors come to see.
The highlight of this festival is the parade of people carrying more than 120 Mikoshi (portable shrines), and splashing water over the Mikoshi and the streets.
Fukagawa Hachiman Festival
August 11th(Sun) - 15th(Thu) 2019
Location: Tomioka Hachimangu Shrine, Fukagawa, Tokyo
Youtube by Asahi Shinbun - http://youtu.be/zCxM3XBVs6Y
Tomioka Hachimangu Shrine (Japanese web page) http://www.tomiokahachimangu.or.jp/htmls/maturih1.html
From Otemachi Subway Station 大手町駅 (Near Tokyo station), take a train on the Tozaisen Subway Line 東西線, then get off at Monzen-nakacho Station. 門前仲町駅 (Travel time 12min.)
3 min. walk to Fukagawa Hachimangu Shrine.