Garden gathers children with special circumstances and trains them as assassins in a place called factories. After enrolling, their names are discarded and the mere mention of their real name will lead to severe punishment.
Members of the Organization can be divided as low-ranking and high-ranking members. Low-ranking members who graduate from the factories are given a name based on the minor arcana, hence Swin and Nadia being known as Three of Swords and Nine of Swords. They are bound by the Garden's strict rules requiring them to cooperate and requiring them to rat out their partner if they attempt to betray or escape the Organization. If two members are caught betraying the Organization, they are purged; however, if one of them exposes the other attempting to betray the Organization, then that person will be spared and granted freedom while the exposed person is purged.
Before the events of Three and Nine, Swin's (Three of Swords) partner was the Ace of Swords. When the two of them failed in an attempt to escape the Organization, the rules dictated that if one of them betrayed the other, that person would be spared. Ace made it look like he was betraying Swin, but in reality, he allowed Swin to kill him thinking he was defending himself against a traitor, because he didn't want Swin to feel the guilt of betraying a partner.
Within the next three years, Nadia, Ace's younger brother, became Swin's next partner. During the events of the book, Nadia is aware of the truth about Ace's "betrayal" of Swin who falsely thinks Nadia seeks to kill him in revenge. The two of them fool their Warden who is supervising them, the Emperor, into thinking Nadia is about to betray Swin, but this is all a ploy; thanks to Swin's sword properties and Nadia's analysis techniques, they are able to overcome the Emperor's gravity manipulation tactics and defeat him. They execute him before leaving the Organization for good.
Similar to Ouroboros, its overseers are named after major arcana and the members they manage after minor arcana. The overseers are equipped with artifacts.The members are always paired to improve the success rate of the operation and to have potential traitors reported or assassinated.
Garden of Swords
Overseer of the Garden of Swords (剣の庭園) is Emperor.
- Ace of Swords (Nadia's older brother, deceased)
- Three of Swords (Swin Abel)
- Nine of Swords (Nadia Rayne)
Garden of Thorns
Overseer of the Garden of Thorns (棘の庭園) is Melchior.
Garden of Aurum
Garden of Rust
Overseer of the Garden of Rust (錆の庭園) is Arioch.
- There are 56 Minor Arcana cards and 22 Major Arcana cards. This would imply a limit on how many members there may be.
- When the Emperor was confronted by Order of the Moonlight Horse member Sharon Kreuger, he remarked that he knew that Sharon was a member of the Moonlight Horse, and Sharon was surprised for him to be aware of this. This foreshadows the connection between Garden and Order of the Moonlight Horse.
- 金黄の園 is also used as alternative spelling in Kuro no Kiseki, Chapter 5: "White Night Carnival" (白夜のカルナヴァル).
- Kuro no Kiseki, Chapter 5: "White Night Carnival" (白夜のカルナヴァル).