When reading manga, there are some good days and some bad days.
This one ended up with one hell of an apocalypse day. Pun intended.
This is the exact reason why I read manga online and only buy the paper form or digital form when I know the manga is a wholesome story. If you don't plan on making a proper beginning, development and, especially in this case, a proper ending, don't start it at all. This one got me hooked sink and sinker for a 3 days as I was reading it during my breaks at my job and, with that ending, I'm so glad I haven't purchased the paper form (if there's one available in my area.)