The Guardians are the student council of Seiyo Academy designed to protect the students and the school, and secretly keep children's heart's eggs safe and preserve them while looking for the Embryo - the legendary heart's egg that has the power to grant wishes, as well as fighting against the Easter Company, a powerful corporation also aimed at obtaining the egg.
This organization was founded by Seiyo Academy's principal, who is named Tsukasa Amakawa - the first King's Chair, also known as the Founding King.
The Guardians are traditionally recruited with four kids with Guardian Characters in four positions known as the King's Chair, Queen's Chair, Jack's Chair, Ace's Chair.
Following the Founding King's instructions, when a person with three Guardian Characters appeared, a special position was granted to that person - Joker. Such person will be given the power to wield the Humpty Lock, which allowed them to purify those heart's eggs whose owners have tainted it with an X, something most Guardian Bearers cannot accomplish.
King's Chair - the leader of the Guardians.
Guardian Apprentice is a term introduced later in the anime. Since most of the Guardians will be graduating at the end of the series, leaving Yaya as the only chair left, they recruit two new members for training in hopes of them someday receive their own Heart's eggs.
- Hotaru - Rikka's Guardian Character
- Tsukasa Amakawa - The first King's Chair
- Temari - Nagihiko's first Guardian Character
- Rima Mashiro - Former Queen's Chair
- Kusukusu - Rima's Guardian Character
- Kukai Soma - Former Jack's Chair.
- Daichi - Kukai's Guardian Character