As the title suggests.

The tutorial section at the beginning was actually set in the present. Everything from Sora's departure to Olympus, to the disastrous battle with Terra-Xehanort and the Demon Tide was a flashback. In fact, the seven hearts the voiceless narrator is referring to Mickey, Donald, Goofy, Riku, Lea, Aqua, and Ven. And the voiceless narrator could be Kairi's heart.

really interesting theory! but it might be overthinking a little bit in some ways.

That could work, the whole thing about seven hearts to save was never really made clear. Because at the start of the game there were only Ven, Terra, Aqua, Naminé, Roxas and Xion, who in need of saving, Axel was already save and I don't think Ansem would be counted.

The game was pretty vague with when that dive took place. I remember reading that the statement "They can take your world. etc" Is reflective of his mindset at the end of the game, so maybe the dive that comes after is also out of order. I can't really imagine which seven hearts would need saving after KH3, but there are seven friends in need of saving at the point you suggested.

27 minutes ago, adrianxxii said:

That could work, the whole thing about seven hearts to save was never really made clear. Because at the start of the game there were only Ven, Terra, Aqua, Naminé, Roxas and Xion, who in need of saving, Axel was already save and I don't think Ansem would be counted.

The game was pretty vague with when that dive took place. I remember reading that the statement "They can take your world. etc" Is reflective of his mindset at the end of the game, so maybe the dive that comes after is also out of order. I can't really imagine which seven hearts would need saving after KH3, but there are seven friends in need of saving at the point you suggested.

you forgot namine 

Just now, ocean's rage said:

you forgot namine 

She's forth in my list between Aqua and Roxas unless yo mean at a different point.

2 hours ago, adrianxxii said:

She's forth in my list between Aqua and Roxas unless yo mean at a different point.

my mistake must have misread it