Hanazono Shrine Bon Odori will held from Aug.1 to Aug.2 at Shinjuku Hanazono Shrine.
(In case of rain on both dates both days, postponing for only one day until 4th of Aug.)
Dancing circle spreads around the tower and participation is free. There are various food stalls as well.
Official Site: http://www.hanazono-jinja.or.jp/mt/top/