The Black Box is an item introduced in Kingdom Hearts χ Back Cover. Originally owned by the Master of Masters, that Box was entrusted to Luxu, who oversaw it for several centuries. Its exact content is unknown.
Maleficent and Pete are looking for this box.
Evil thinks it has been hidden since the fairy tale era, but no one knows where it is or what exactly it contains.
The Black Box is a large black chest, large enough for a single person to be unable to lift it off the ground. It has thirteen locks of silver and red color; three on the left side, three on the right side, and seven on the front. The central lock of the front is larger than the others.
On the top of the Box is an emblem with a silver outline and a red central part. The outline forms thirteen points outward, and seven inwards. The central part bears the inscription "χsuper" on it.
Kingdom Hearts: χ Back Cover
Originally, the Black Box is a mysterious chest owned by the Master of Masters. After asking his sixth apprentice - Luxu - to observe the events and the future through The Gazing Eye, Master reveals to her the Black Box, adding that she must have remained hidden. When Luxu asks what the Box contains, the Master is content to answer that it is a secret, and that Luxu shouldn't open it.
However, at the insistence of his pupil, the Master whispers in his ear the contents of the Box. The answer greatly surprises Luxu, who asks why. The Master just answers him that he would see in due time.
Subsequently, obeying his Master, Luxu disappears into the Badlands with The Gazing Eye and the Black Box.
Kingdom Hearts: 0.2 Birth by Sleep -A Fragmentary Passage-
After the Keyblade War, Luxu observed the conclusion of the events with The Gazing Eye. The black box is at his side, placed on the ground.
Between Kingdom Hearts: 0.2 Birth by Sleep -A Fragmentary Passage- and Kingdom Hearts III
In accordance with the mission entrusted by his Master, Luxu hides the Black Box in an unknown place. Then, in order to fulfill his mission and cross the centuries, he transfers his receptacle heart into a receptacle until he becomes Braig, then Xigbar.
Throughout the ages, the existence of the Black Box eventually becomes almost unknown to all.
At one point, Maleficent meets an individual dressed in a black coat who speaks to him about the Black Box, and who tells him that it contains a Book of Prophecies. We don't know who the individual is in black, and whether he told the truth or not. Determined to find the Box and its contents, Maleficent enlists her second, Pete, to investigate different worlds.
Kingdom Hearts III
Maleficent and Pete go first to Olympus, to ask for information from their former ally, Hades. The latter mentions a black box that Zeus had hidden on Earth a long time ago. Interested in the information, Maleficent learns from Hades that this box would be hidden somewhere in Thebes, before going there with Pete. There, the duo meets Sora, Donald and Goofy and Pete evokes their search for the Black Box in front of them.
Thereafter, in the Gardens of Thebes, Pete is charged by Maleficent to dig until finding the Box. Pete expresses doubts about the existence of the Black Box and the so-called Book inside. However, he eventually found the box evoked by Hades: the Pandora's Box. Disappointed, Maleficent orders Pete to leave this box where he found it, before declaring that they are done with Olympus. However, without the duo noticing it, they are seen off by Xigbar.
Xigbar then reports the existence of the Black Box to the rest of the Thirteen Seekers of Darkness. Without revealing details about the true nature of the object or what it actually contains, Xigbar just tells the rest of the group that the Box is real and contains "hope". Luxord is the member responsible for finding the Box for the rest of the group.
Thereafter, Maleficent and Pete continue their search in the Kingdom of Corona, without result. Pete reaffirms his doubts about the existence of the Box, but Maleficent asserts that it is real because it would be "written".
In the Caribbean, Luxord is investigating to find the Black Box, accompanied by Vexen. Having learned of the existence of Davy Jones, a heartless but existing living being, Vexen believes that the secret must be in the Box, but Luxord cuts his curiosity, claiming that they have just been asked to seize and bring back the box. Then, Luxord appears to Sora, Donald, Goofy and Jack Sparrow to ask them for information about a box, or even a chest.
Believing that Luxord is talking about the chest containing Davy Jones' heart, Jack remains imprecise on the details, arguing that he knows of a chest but that it is better to stay away from it. Luxord then offers a boat race to Jack and his group: the first ones who arrive at Port Royal wins. If he wins, Luxord asks Jack to tell him everything on the chest; and if he loses, he undertakes to offer him what he desires. Jack agrees, and manages to win the race with Sora, Donald and Goofy.
Feigning defeat, Luxord reappears to the group, and asks Jack what he wants as a reward. Proud to win, Jack says he wants the chest aboard the Dutchman, without realizing that Luxord has tricked him. Knowing now the location of the chest, Luxord leaves in the direction of the Flying Dutchman.
Later, after the appearance of the Maelstrom, Luxord reappears alongside Sora, Donald and Goofy, having finally found the Flying Dutchman. When Sora mentions that the Dutchman's chest contains Davy Jones' heart, and that it can't be the chest he's looking for, Luxord gives a slight laugh, arguing that no one knows what's in the box he's looking for. Sora then asks why he needs it and how he can know if it's the right one. Luxord replies that the superiors of the Organization didn't deign to give this information, but said that the box contained "hope". Luxord then invokes tentacles to attack the Black Pearl, hoping to distract everyone while he searches for the box on the Dutchman.
On Davy Jones' boat, Luxord appears to Jack, who has just recovered the cursed chest. The Organization member requests that the pirate give him the chest. Before Luxord can ask for talks, Jack retorts that they are busy enough there, then makes Luxord smell his breath, causing him to fall from the edge of the boat.
In Twilight Town, Pete explains that he is tired of searching for the Box, arguing that there was nothing in every box they found. Maleficent approves, and announces that their search stops at this moment, arguing that one can't find the Box since the Box doesn't exist. Much to Pete's astonishment, Maleficent explains that Box doesn't exist now, but that the coming Keyblade War will bring the Box. She adds that once they have the Box, their real mission will begin.
Following Master Xehanort's defeat, Xigbar finds The Gazing Eye at the Keyblade Graveyard, the Black Box at his side. Then, he summons four of the five Foretellers: Ira, Aced, Invi and Gula before revealing himself as the current incarnation of Luxu. The group then starts a long discussion on the role that Luxu played; all observing the black box on the ground. In the distance, Maleficent and Pete observe the group meeting before leaving.
- The inscription "χsuper" on the Black Box is a reference to the Latin names of the Seven Deadly Sins, since "super" is the diminutive of superbia, that is, pride.
- The other six sins are referenced in the names of the six apprentices of the Master of Masters: "Aced" is a diminutive of acedia, "sloth"; "Ava" is a diminutive of avaritia, greed; Gula means "gluttony"; Ira means "wrath"; "Invi" is a diminutive of invidia, envy; and "Luxu" is a diminutive of luxuria, lust.