Amu Hinamori is a student at Seiyo Elementary, where she has a reputation for being "cool and spicy". However, her real personality is that of a very shy girl who has trouble showing her true self. One night, Amu wishes for the courage to be reborn as her "would-be" self, and the next morning Amu finds three brightly colored eggs—red, blue, and green—in her bed, which hatch into three Guardian Characters: Ran, Miki, and Su. The Guardian Characters aid Amu in discovering who she truly is and help fulfill Amu's dreams. Amu's life becomes much more complex as she struggles to deal with her "would-be" selves and the Seiyo Elementary's Guardians, who recruit Amu to search for the X Eggs and X Characters, the corrupted forms of peoples' dreams.

However, the Easter Company is extracting people's eggs in search of a special egg called the Embryo. The Embryo is believed to able to grant any wish to the one who possesses it. Nevertheless, the process creates X Eggs and X Characters.