After being told that it's tradition to send a few students from their academy to dance every year, Hiro Amanokawa with Gammamon and classmate, Kotaro Nomura, go to Ashihara Girls Junior High School in Kamakura to participate in their Summer "Wakagimi Dance."
While preparing for their dance, they learn that the female student who is supposed to play the role of the wakagimi suddenly fell ill, and Hiro must take her place.
Not far off, the Digimon, Doumon, who can manipulate onmyo magic, plots to revive the spirit of the Hojo clan's young lord. He had died on this land. Along with the Lord, Doumon will resurrect the Japanese bakufu after 700 years.
During the dance, Doumon kidnaps Hiro, who is dressed as the wakagimi. Hiro will be used as a vessel for the spirit of the young lord. In addition, Doumon is turning the townspeople into shikigami and controlling them. His plan is to conquer and rule the rest of the land of Kamakura.
Gammamon is left alone and is looking for Hiro when a mysterious Digimon, Espimon, suddenly appears. Together, the two work together to rescue Hiro.
When they find Hiro, Espimon tells Gammamon to destroy the talisman on the boy's chest. Once that is done, Hiro returns to normal. Gammamon evolves to Wezengammamon then Canoweissmon to bring down Doumon.
As it turned out Doumon himself was taken over by the vengeful spirits of the Hojo clan. Once he was cleansed of the spirits, Doumon turned everyone back to normal.
NOTE: Gammamon had called Ruli, but once they arrived in Kamakura, everything had already been resolved.