The ending
What happened to Morisaki? Why did he stay behind?
shareHe spent 10 years of his life looking for Agartha. Plus, he had a hard enough time finding meaning in his life without his wife, it'd be harder still to start over casting aside the place he's been searching for. I think it has to do more with him not having a place in our world anymore.
share[deleted]
Plus, there is the fact that the Arch Angels are likely to going be searching for him after he betrayed them. I'm pretty sure Morisaki doesn't want to be captured by them thus providing another motive for him to stay in Agartha rather than return to the upper world.
Welcome to my Nightmare- Freddy Krueger