[Free]

Spoiler for speculation:

If it really turns out to be some comatose or near-death world, I'll be greatly disappointed. However, I'm going to trust Angel, that she never lies, so since she said they're all dead, they are all dead. D:

And Angel is just Angel. I don't recall her ever giving her name, just "I'm the school council president". Angel(Tenshi) is just the name Yurippe tagged onto her, to which she said she is not, not Angel, nor Tenshi.

Also, the radio said the OP and ED are very meaningful, I'm guessing especially the last few lines of the OP, and the overarching theme of the ED...