Board Thread:Questions and Answers/@comment-5972544-20130724143413/@comment-30036337-20161011085813

This may be quite late as I've only watched this today. I think Humpnie's theory explains why he died (I'm basing this on the anime since I haven't read the manga). God didn't abandon mankind but granted them their wishes. His wish 15 years ago when his health changed for the better was for it to go on forever thus he gained immortality. Then Hana disappeared and he realized that he would be the last human left at the very end his wish changed to 'dying happily with family, friends crying over him and a bit of regret' which was fulfilled to the t at the time he died. He had a family and a friend with him and regretting the things he couldn't say.