I don't get why some guys are freaked out about things such as Bando surviving (he definitely got his soldiers cut off now, if you know what I mean xD) and Lucy and Nyuu resurrecting. I mean, the whole series was about horned humans with magical arms that could do pretty much anything, but those parts were too off the mark? Anything goes in your own manga series, could've drawn Goku at the end saving the world and it would still be feasible, because the manga is the writer's creation, after all.
Anyway, I liked the happy ending, giving the whole series an 8/10, as some things weren't explained as much as I wanted. I also feel the ending could've developed a bit more, as we are unsure of the future of characters like Nozomi and Mayu.
Also, what's up with people freaking out about the cousin relationship? It's completely normal in Japan, we are not reading Marvel/DC comics here. There are several other manga/anime/LNs etc. that portray or mention similar relationships. For example, Sword Art Online. We shouldn't judge if such a thing is part of Japan. It's quite ironic if you do when you're reading a manga or whatever.
Back to the story...they left it ambiguous whether the spy and Anna will be safe or not...I mean, the fact they're shown alive probably means they'll survive later on, but Anna forgot how to leave the cave and the island collapsed. One more miracle we'll not witness! :|
Pretty much a fail that 10 years passed and Kouta never looked at the stone closely enough. A child could look better in a day than he could in 10 years, come on bro... Fortunately, it was not anything that was time-essential.
All in all, it was a great ride, too much strife but in the end we get a satisfying ending. While some may complain it may not be feasible according to their own theories, it's still better than having all the characters we care about just stay dead. If you want shit like that, go read any dystopian book ever written.
Cheers.