Amu Hinamori and the Seiyo Elementary Guardians have set out to find and purify the X Eggs in their quest to obtain the powerful Embryo, rumored to grant any wish. They must secure the Embryo before their nemesis, the Easter Corporation, does. Their mission becomes more complicated when Easter hires Lulu de Morcerf, a reserved girl with a ruby necklace that can transform Heart Eggs into Mystery Eggs, which prove harder to purify than X Eggs and can trigger a Character Transformation. The Guardians must locate the source of this new danger and put an end to it before it spirals out of control. Can they succeed in acquiring the Embryo and managing the Mystery Eggs simultaneously with these two pressing objectives?