The light of lanterns floating on the water of Sumida-gawa illuminating the dark pool of the river makes an ease atmosphere. This beautiful scenery takes place every year during what the Japanese call the Tōrō Nagashi. Tōrō Nagashi (灯籠流し) is a Japanese ceremony or a symbol of summer celebrating by releasing the beauty of paper lanterns floating along the calm Sumida-gawa River. It is held during the Bon festival at the middle of July or August in the evening when the sky is going dark. People belief, by doing the ceremony, that the spirit of ancestors will ride down to the river and will return to the afterlife (Japanese belief that humans come from water). the ancestors souls are represented by the light of lanterns.
Tōrō Nagashi can be held on other days besides the day of Bon, such as during commemoration of those who lost their beloved in the bombing of Hiroshima and Nagasaki, also during the Tohoku tsunami and earthquake hit Japan.
Tōrō (paper lanterns) are Japanese traditional lantern made from wooden base and frame. The frame is wrapped with paper so the fire inside the Tōrō will not be extinguished by the wind. The paper can be in various color or one color. You may draw anything on the paper. The white paper wrapped the lanterns symbolize people who have died in the past year.
The lanterns are available for purchase, you can contact Asakusa Tourist Federation in the area where the ceremony take place.
Apart from Asakusa, there are some places where the ceremony is held, such as in Abukuma (Fukushima Prefecture) and Arashima (Kyoto) along with fireworks display, The Yokohama Ooka River (Kanagawa Prefecture) and several also outside Japan such as in Hawaii organized by Shinnyo-en, which is held as a Memorial Day for the Battle of the Pearl Harbor (WW2).
Tōrō Nagashi was held in mid August in 2015 (In 2017 it was held on August 12th). If you are interested in the ceremony, you can go to Sumida Park Shinsui Terrace. You can walk about three minutes from the Asakusa Station (Tokyo Metro Ginza Line, Tobu Isesaki Line or Toei Asakusa Line) or from Toei Bus Tobu Asakusa-ekimae.