Keijo, a new form of gambling sport, has taken Japan by storm. While standing on floating circular platforms, players must defeat their opponents by using only their breasts and buttocks. Drawn into this female-only sport in hopes of making a fortune and escaping poverty, 17-year-old Nozomi Kaminashi decides to abandon her gymnastics career to apply for the Setouchi Keijo Training School alongside Sayaka Miyata, her new friend and former judo athlete. In the upcoming exam, the girls will have to utilize the utmost of their abilities to qualify as students of the school. With only the final goal in mind, Nozomi and Sayaka steel themselves to compete against participants from all over the country.

Following the conclusion of Keijo!!!!!!!!, Daichi Sorayomi revealed in a blog post that prior to the anime's airing, he was told to conclude the series by the time the anime ended. He also said that he did not receive much support by publisher Shogakukan in producing and popularizing the series.