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.
Knowing he will soon disappear from the world, the Master of Masters gives new names to his six apprentices. He also bestows a copy of his Book of Prophecies upon five of them and assigns a unique role to each.
To his sixth apprentice, Luxu, the Master of Masters grants his Keyblade and a mysterious box that says "χ Super" on it.

The Master of Masters behaves in an unpredictable and eccentric manner. 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 is immensely intelligent, as he is able to create new entities such as the Chirithy. Kingdom Hearts Wiki