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The Gathering is the secret ending of Kingdom Hearts II; the same scene is known as simply "Gathering" in Kingdom Hearts Birth by Sleep. Sunset Horizons is the piece of backing soundtrack used during the video. The term "The Gathering" first appeared in the Deep Dive video.^[1]

Synopsis

The video starts with the view of a desert. A semi-transparent Ansem's Report scrolls down the screen where one of them explains a detailed article on the Keyblade. There are a few shots of metal objects lying in the sand. The screen shows a man in armor, Terra, standing amidst the desert waste, on the remains of a large construct decorated with various spikes. He looks to one side and sees another armored figure, Aqua, approaching. Terra turns his head again and sees the third figure, Ventus, also approaching. As Aqua and Ventus come closer, Terra walks towards three Keyblades standing alone in the wasteland, as the thing he was standing on dissipates in the same fashion as a dying Nobody. The three Keyblades are the Kingdom Key, the Way to the Dawn, and the Kingdom Key D. Terra takes the Kingdom Key, Ventus takes the Way to the Dawn, and Aqua takes the Kingdom Key D.

The screen zooms out to show Terra, Ven, and Aqua standing in the center of a field of Keychain-less Keyblades, one of which resembles the Fenrir Keyblade. They stand still for a few moments before something catches their attention and they all look up. A figure, too blurry to make out in the heat, is walking towards the three Keybearers, and words appear briefly on the screen in this order:

Master of Keyblade
The lost two
Memory of Xehanort
Chasers
Keyblade War
It all began with...
"Birth by sleep".

Possible meanings

"Master of Keyblade" could refer to Master Xehanort, Master Eraqus, or possibly the Mark of Mastery. It could possibly even refer to Aqua, who becomes a Keyblade Master after passing her Mark of Mastery Exam during Kingdom Hearts Birth by Sleep.
"The lost two" likely refers to Master Xehanort and Vanitas, or Ventus and Terra. It could also mean Ven and Aqua, since Terra's body has been seen throughout the series, but neither of them had been seen before this.
"Memory of Xehanort" refers to the memories that Xehanort lost when he developed amnesia. Nomura has explained that these are related to the reason that Sora and Roxas can dual-wield, and why Roxas seems to have a heart.
"Chasers" could refer to Terra, Aqua, and Ven, who are chasing Master Xehanort and Vanitas. It is possible that "Chaser" is a rank, as well, as in the real world, "chaser" refers to one who engraves metal.
"Keyblade War" refers to an ancient war fought between Keyblade wielders.
"Birth by Sleep" refers to how everything is "born through sleep". It may refer to the Awakening of new Keyblade masters.

Characters in order of appearance

Unlock criteria

The conditions to unlock the video The Gathering vary according with the difficulty level chosen:

Kingdom Hearts II

Beginner Mode - Not accessible
Standard Mode - Complete Jiminy's Journal
Proud Mode - Finish the game and complete all worlds

Kingdom Hearts II Final Mix

Finish the game on any difficulty

Application to subsequent games

Prior to the release of Final Mix, which featured Birth by Sleep, a secret video continuing The Gathering, there was heavy speculation as to the identities of the three armored figures. Once it was released, Nomura revealed the identities of Terra, Ventus, and Aqua, noting that they had a connection to Sora, Riku, Kairi and Xehanort, though he refused to specify to avoid spoiling plot points. This scene ultimately occurs in Birth By Sleep ten years before the events of Kingdom Hearts, where it is followed by a vicious battle between the three warriors and Master Xehanort and Vanitas.

The Gathering was conceptual. The actual meeting in the Keyblade Graveyard of Terra, Ventus, and Aqua does not feature the three armored. Nomura has said that they were depicted as such in The Gathering because he did not have final designs worked out for any of them. Additionally, Terra does not stand on a vanishing metal structure, nor do any of the three Keyblade wielders pick up Keyblades associated with Sora, Riku, or Mickey. It is unclear what either of these parts may have been planned to mean. In Birth By Sleep, Terra picks Riku as his successor, Ventus fuses his heart with Sora's, and Aqua accidentally picks Kairi. It is thus possible that the appearance of the Kingdom Key, Way to Dawn, and Kingdom Key D was meant to symbolize this succession, though the choice of Mickey is not consistent with Birth by Sleep, as he was still wielding the Star Seeker, and the Keyblades are mismatched between the three.