who's the seventh? (kingdom hearts)

[mecurylighthouse]

I recently have been finishing up Kingdom hearts dream drop distance but i cant figure some thing out. Is Kairi actully the seventh gaurdian of light?
[spoiler]In the secret ending it shows that she will learn to use a keyblade[/spoiler]
or is it [spoiler]Axel[/spoiler] or roxas? someone help
PS if your wondering why i think its roxas in the opening cutscene it shows riku, sora, mickey, aqua, terra, ventus, donald, goofy and, roxas jumping at Xehanort im pretty sure that it represents the seven AKA
[spoiler]the Clash of the thirteen darknesses and seven lights[/spoiler]