This review contains no spoilers. This is my first review on the site, but I will try to share my experience about this work. I started to read this work because I found the proposal of having only one character in a world where entering us here is totally possible to happen. You create several theories as to why the people of that world disappeared and this is very interesting to think about, is it that people died of some disease, or were kidnapped by some alien or even just playing a prank. Over time a few other characters will appear with well-defined goals and you will start tocreate new theories, although the manga has a little hentai and this is a focus it is still a great read.