The most popular festival in Japan to honor the deceased is called Obon お盆. It is of Buddhist origin and has been held since five centuries ago.
One of the most beautiful rituals of this festivity is the Tourou Nagashi 灯籠流し, which is to put paper lanterns at nightfall in the course of a river, one for each person you want to honor. In contrast to the dark, a similar of a fire dragon figure is created in the riverbed.
This event mainly takes place in August and there are usually fireworks, traditional dances like the Bon Odori and stalls of food and drink for attendees.