I think the only way to do all of them justice is Kogarashi remembered all the branching timeline/dream and embrace the harem.
They're are using each of their connection to cure him so its not far fetch for him to have all those memories when he became whole again.
Ryuuzen is a sadist, she put the whole harem into a sleep that gives them future visions, only to keep them aware of the fact they are in a dream and that their dream lives will never happen in "real" life, whatever that means