The event originated from the naval battle between the Genpei clans, also known as the 'boat rowing competition.' Participants are divided into two groups, the Genji and the Heike, with six rowers on each of the two traditional Japanese boats. The competition involves splashing seawater at each other. It is held on a Sunday around the 5th day of the 5th lunar month, typically the day after 'Hittaka.'