Firework Artisan Kagi is a representation of The Kagiya (鍵屋) guild of pyrotechnicians, and perhaps Yahei of Kagi-ya himself.
When the land of Japan was united under Tokugawa leyasu in the early 17th century, both swords and explosives were put under the strict control of the shogunate. Agrarian troops and artisans who had dabbled in gunpowder lost their positions, so the art of explosives began to spread among the townspeople and the mountain villages. One of those hanabi ("fireflowers" or fireworks) artisans was known as Yahei of Kagi-ya.
The Sumidagawa Fireworks Festival, originally called Ryōgoku Kawabiraki (両国川開き), had become an established tradition by 1810, and rivalries began to emerge over control of each year's festival.
The Tamaya (玉屋) and Kagiya (鍵屋) guilds of pyrotechnicians quickly became the two major rivals, initiating the tradition of the competition. Each guild would try to impress the onlookers, out-doing the other guild, in order to gain popularity and support. The number of onlookers steadily grew, and they began to shout out the names of their favorite fireworks artists.