[Setsuna understands that, so he nods in acknowledgement. It's also to agree to the boy's own words. That's right, Allelujah— surely even Hallelujah, would have liked him to continue on smiling.]
It will not be the end. I am certain that you will see him again.
[Just like Setsuna... As he left and came back several times, even though he can't remember them happening. In the end, he's able to find himself back here again.]