The story of Extreme Hearts is set in the near future, when the hobby of "Hyper Sports" (which are enhanced with special gear and power-up items) has become popular among children and adults alike. The story focuses on Hiyori Hayama, a second year high school student who initially has no connection to "Hyper Sports", but after a chance encounter this begins to change as Hiyori and her friends grow closer and pursue their athletic dreams.