Yeah... The Blanca part wasnt really explained in the end... Especially her connection to Cooro... But this must be one of those things that are left to the readers to imagine and figure out on their one... I can imagine a reason, but I have to think a while before I finally have a reason to that.
Anyway, those last chapters, the Cooro arc, was making me feel... sad and worried... I dont know, but the feeling of it became much more dark when it come to the history of Cooro (like it said, opening the Pandora box). Much deeper then the rest, in my opnion; and that specially because it showed something not so evident, I think. Cause it was centered in Cooro, it was more clear to see him, a part more hidden of him... Its late at night and I think I'll starting to think I'm saying bullshit here... Anyway, here's my thought of it...
The ending was beautifull. Nothing else is needed to say, I guess.