Amu Hinamori is a timid girl who finds it hard to make friends, partly because rumors at school paint her as "cool and spicy." Hoping to show everyone who she really is, she wakes up to discover three brightly decorated eggs on her bed. Each "Heart Egg" holds a Guardian Character—an embodiment of someone"s ideal self and dreams. With Ran, Miki, and Su beside her, Amu finally feels she can express her true self. Yet things rarely go as expected.
The sudden appearance of Amu"s Guardians catches the eye of the Seiyo Elementary Guardians, a student‑council–like group where each member has their own Guardian. Because Amu possesses multiple Guardians, she is recruited as the Guardians" "Joker," tasked with finding X Eggs—corrupted versions of Heart Eggs.
As she becomes involved in the Guardians" quest, Amu learns more about these mysterious characters, the X Eggs, and an organization that seems to be at the center of it all.