It has to be a flash back because in Ansem Report #13 Ansem says
Only one mystery remains.
How did Xehanort manage to open the door that appeared in the basement of my castle...?
and these reports were written before KH2 took place so I think that its a flashback. Heres the whole report if you want to further investigate.
Secret Ansem Report #13
--------------------------------------------------------------------------------
Tomorrow Sora awakens.
My long and drawn-out revenge is nearing its end.
Xehanort, who took everything away from me. Though as a Heartless he is no more, as the leader of Organization XIII his ambition once again is to capture Kingdom Hearts, the most colossal heart of all.
His Heartless had attempted to draw out the great darkness of Kingdom Hearts, created from the hearts of all worlds. His Nobody, however, is now almost finished gathering human hearts to be assimilated into Kingdom Hearts as well.
The fool!
Only one mystery remains.
How did Xehanort manage to open the door that appeared in the basement of my castle...?
No... any theory posited now, wen everything is nearing completion, would be meaningless.
Roxas, Ansem, Namine...
They defy all logic, yet there they are: singular exceptions to the rule.
The theories proposed by me and by Organization XIII have been blown to pieces by a handful of strong-hearted individuals.
Sora, Kairi, Riku.
Ah, yes- Riku.
Though his heart has its weaknesses, making it prone to darkness, he found support in the hope he discovered beyond suffering.
This hope allowed him to stand his ground and turn the darkness in his heart from an enemy into his greatest weapon.
When all this is over, it is my fervent hope that he will be able to return with Sora to his island.
If I can, I should like to return to Radiant Garden, to look once more upon the beautiful water, the lovely flowers, and the hopeful smiles of the people.
Dear King, my friend!
I believe that, at some point in time, you will come across these, my truthful accounts.
How I wish I could have chatted with you again.
I was a fool, obsessed with revenge.
Forgive me.
Only one mystery remains.
How did Xehanort manage to open the door that appeared in the basement of my castle...?
and these reports were written before KH2 took place so I think that its a flashback. Heres the whole report if you want to further investigate.
Secret Ansem Report #13
--------------------------------------------------------------------------------
Tomorrow Sora awakens.
My long and drawn-out revenge is nearing its end.
Xehanort, who took everything away from me. Though as a Heartless he is no more, as the leader of Organization XIII his ambition once again is to capture Kingdom Hearts, the most colossal heart of all.
His Heartless had attempted to draw out the great darkness of Kingdom Hearts, created from the hearts of all worlds. His Nobody, however, is now almost finished gathering human hearts to be assimilated into Kingdom Hearts as well.
The fool!
Only one mystery remains.
How did Xehanort manage to open the door that appeared in the basement of my castle...?
No... any theory posited now, wen everything is nearing completion, would be meaningless.
Roxas, Ansem, Namine...
They defy all logic, yet there they are: singular exceptions to the rule.
The theories proposed by me and by Organization XIII have been blown to pieces by a handful of strong-hearted individuals.
Sora, Kairi, Riku.
Ah, yes- Riku.
Though his heart has its weaknesses, making it prone to darkness, he found support in the hope he discovered beyond suffering.
This hope allowed him to stand his ground and turn the darkness in his heart from an enemy into his greatest weapon.
When all this is over, it is my fervent hope that he will be able to return with Sora to his island.
If I can, I should like to return to Radiant Garden, to look once more upon the beautiful water, the lovely flowers, and the hopeful smiles of the people.
Dear King, my friend!
I believe that, at some point in time, you will come across these, my truthful accounts.
How I wish I could have chatted with you again.
I was a fool, obsessed with revenge.
Forgive me.
