(Hibiya-Marunouchi Bon Odori Dancingevent Friday 25 and Saturday 26, August?)?
http://www.gotokyo.org/jp/kanko/chiyoda/event/hibiya_bonodori.html?PHPSESSID=lrur5og548dtvqd4h53256tkk0
It is not this evening but you
may have to prepare yokata ane other items for dancing.