Amu Hinamori and the Seiyo Academy Guardians are back to their council duties after stopping the Easter Corporation's threat. They take care of any X Eggs they come across while dealing with the uncertainty of the next Guardians Council due to four members graduating. To ensure continuity, the team hires two "Guardian Apprentices" with the hope that they will find their Heart's Egg. Rikka Hiiragi is among the selected apprentices, a lively girl who can communicate with X Eggs, an ability that amazes the Guardians. However, Rikka fears rejection if they learn about her extraordinary gift.