The heroine of the story, Amu Hinamori, is a student at Seiyo Elementary.[3] At first glance, her classmates refer to her as "cool and spicy" and rumors speculate about her personal life. However, her real personality is that of a very shy girl who has trouble showing her true personality. One night, Amu wishes for the courage to show her "would-be" self, and the next morning finds three brightly
colored eggs—red, blue, and green—in her bed. At first, she is alarmed, but realizes she must have really wished to change. 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 each have a Guardian Character of their own. Later on,they recruit Amu as the "Joker" to search for X Eggs and X Characters, the corrupted forms of people's dreams, so the Guardians can purify their dreams. Meanwhile, the Easter Company is extracting people's eggs in search of a special egg called the Embryo. The Embryo is believed to grant any wish to the one who possesses it. However, the process creates X Eggs and X Characters. It is described as an all white egg while normal heart's eggs have a yellow heart and yellow wings on it. Later on in the series, a fourth (yellow) egg named Diamond is born. Unlike Amu's other Guardian Characters, she is only seen a few times in the series. Due to Amu's mixed feelings before Diamond was born, she becomes an X character and is "stolen" by Utau Hoshina, who uses Diamond for her concerts planned by Easter. Later on, Diamond is purified and becomes a regular Guardian Character. She would then would appear in times of heavy crisis.
