According to the Japanese tradition, during the first day of Obon the souls of the ancestors are coming home, to reunite with the family. To help them find their way home, fires or paper lanterns are lit in front of the house or inside, in the Butsudan (Buddhist altar).
During the last day of the celebration, the souls are guided back to their world with Toro nagashi floating paper lanterns (toro means "lantern" and nagashi means "to cruise, flow"), like the ones in my photo, photographed on the Shinobazu Pond from Ueno, Tokyo.
EXIF info:
Nikon D300
Lens: VR 70-300mm F/4.5-5.6G
Focal Length: 165mm
Aperture: F/6.3
Shutter Speed: 1/60s
ISO Sensitivity: ISO 1600