I do know that the communicator spoke of Kuu’s laughter as being in Rakka’s mind. What about those drops of water? What caused them? Is that caused by the wall because of Rakka’s being there, and something that would not exist in the wall without her presence?

You’re right about how Kuu knew her day of flight was coming, but I wonder if she knew about the day of flight. Did she actually hear/learn about the day of flight at some point prior to the drip-drip-drip in her mind brimming the edge of the cup?

Sometimes I might not remember little details from episode to episode (which is one reason I write them down here). Whether I go back and refer to them while still watching the series is another thing entirely =P

Hyoko left with Reki. If you remember, there was a flashback of them departing together on a scooter (or the scooter really).

I thought Kuu’s supposed laughter was explained as something created by Rakka’s mind. It does not exist in the wall independently of Rakka. This brings up the whole question of the next stage, when a haibane succeeds in their second chance and can die in peace. The very existence of Glie in haibane universe suggests that the information encoding their souls does not just turn into a small amount of heat after death, like in our world. Can be anything really, for example a reincarnation. It’s possible that Kami’s motivation to create such an elaborate setup in the first place was to cleanse souls for ease of reusal. It’s pure fantasy though.

Yes Reki knows. Kuu knew it, so why would not Reki? She might’ve even seen her own halo flickering in a mirror somewhere. Actually your first paragraph says it.

[Please don't mind if I've removed one word from your post. It's my extreme strictness on general audience dialogue requirements. --Administration]