The Master of Masters

The Master of Masters, also known simply as the Master, is a Keyblade Master who appears in Kingdom Hearts χ. Gifted with the power of foresight, he writes the Book of Prophecies and trains six apprentices: Ira, Aced, Invi, Gula, Ava, and Luxu.

Before Kingdom Hearts χ
During the "age of fairy tales", when the Master of Masters was a boy, the Keyblade War, a conflict between light and darkness began. This conflict continued without end for an unknown period of time. At some point in his adulthood, the Master of Masters creates the Book of Prophecies by means of his "Gazing Eye", which allows him to view any events in the future it will witness. The Master takes six apprentices, gifting each of them Keyblades forged from their hearts, who are then renamed Aced, Ava, Gula, Invi, Ira, and Luxu. Excluding Luxu, the apprentices are chosen to be foretellers and receive copies of the Book of Prophecies, which depicts an event known as the Keyblade War, in which light would expire and the world would reach its end.

He meets with Luxu frequently in the Control Room, where the Master briefly tells him about his past, an ongoing Keyblade War and how the world would be destroyed and then rebuilt. The Master reveals he plans to the world's fate in the hands of others, a fact that shocks Luxu, though the former assures the latter that most of Ava's Dandelions will be be sent to the new world. Seeing that Luxu was depressed about the Keyblade wielders not being able to do against the impending darkness, the Master informed him that there is a way to defeat darkness, but it would require extensive planning and many lifetimes to accomplish.

Knowing he will soon disappear from the world, the Master assigns a unique role to each of his disciples. The Master bestows Luxu with the No Name Keyblade that contains the Master's Gazing Eye and instructs him to pass the No Name from master to apprentice so that the Gazing Eye can relay future events back to him. The Master then orders Luxu to simply watch things unfold between the other apprentices and keep the contents of his Black Box a secret from the others. Sometime later, the Master selects Ira to succeed him as leader of the foretellers in the event of his disappearance. While Ira resolves to gather as many Keyblade wielders as possible to maintain the balance of power in an effort to avert the Keyblade War, the Master claims that the war is inevitable.

After Luxu leaves to fulfill his role, the Master assigns the rest of the foretellers with their own individual roles: Invi is tasked to observe her fellow Foretellers and act as a mediator; Aced is to become Ira's right-hand man when Ira takes over as leader; Gula is assigned to discern the identity of the traitor mentioned in the Lost Page and stop them; and Ava is instructed to avoid the imminent battles in favor of gathering exceptional Keyblade wielders, regardless of their Unions, to be part of a separate faction called the Dandelions, who would venture to another world to ensure the survival of the light. The Master provides Ava with a list of five Keyblade wielders she must gather to succeed the foretellers following the Keyblade War, with only one of them meant to receive a copy of the Book of Prophecies.

The Master soon introduced the foretellers to his latest creation, the Chirithy. Though the Spirit Chirithy are meant to aid Keyblade wielders in their endeavors, the Master warns them that if a wielder falls to darkness, so will their Chirithy, causing them to transform into a Nightmare.

Without warning, the Master disappears from the world, and although Ava and Gula actively seek him out, they are unable to locate him.

Kingdom Hearts χ
One night, Chirithy shows a dream in which the Master of Masters is speaking to the other foretellers in the Foretellers' Chamber, though Nightmare Chirithy quickly puts a stop to this dream.

Between Kingdom Hearts χ and Kingdom Hearts Birth by Sleep
Many generations later the Master makes contact with a young Xehanort, gifting the boy with a black coat, and has him tour the worlds to broaden his horizons. Meeting in the Keyblade Graveyard, the Master is surprised by Xehanort's revelation to side with darkness to prevent the World from falling into chaos. Encouraging the youth to believe solely in what he sees and that he will one day be strong enough to not need the black coat, the Master attempts to leave.

However, Xehanort asks for his name; the Master gives his name, shocking Xehanort, continuing on to say he is a Lost Master. Departing, the Master recites "May your heart be your guiding key."

Kingdom Hearts III
Xigbar assisted Xehanort in kindling the Keyblade War as part of his plans to convene the foretellers, followed by the Master of Masters.

After the defeat of Master Xehanort, in Quadratum, on the roof of a skyscraper, the Master of Masters observes the spherical moon, and compares it to Kingdom Hearts.

Design
The Master of Masters wears a black coat, which obscures his features. One of his eyes, embedded in the No Name Keyblade, is blue with a vertical, slit-shaped pupil.

Personality
Although highly revered for his immense intelligence and foresight, the Master of Masters behaves in an unpredictable and eccentric manner, making his true intentions difficult to discern. He is a mischievous and playful individual, appearing curious about what will become of the world after the Keyblade War, in spite of already knowing the answer. Although he demonstrates a more serious side to his persona, especially when talking about the specific roles he had given to the foretellers, he has a tendency to weave in and out of serious moments at a mere whim, being somber at one moment and laughing playfully the next.

He shares a close relationship with his disciples, having inculcated an unquestioning loyalty to him within them, and treats them affectionately, though his eccentricity often baffles them. In spite of this, he manipulates them into starting the Keyblade War, without any apparent qualms.

One definite trait of the Master is his belief that the "truth" lies in what is seen and not spoken. He also claims to be afraid of facing the darkness without his black coat.

Abilities
The Master of Masters can spawn Keyblades from the hearts of others. He is highly intelligent, as he is able to create new entities such as the Chirithy Dream Eaters, and he is able to see the future with his Gazing Eye.