tl;dr: A strange story featuring essentially only two characters with a weird relationship told in an an incredibly interesting fashion.  

This manga had a strange but very interesting story that worked very well with the way the story was told. In essence, there are only really two characters in this work, the guy and the girl. These two characters are such a focus of this work, that it doesn’t even give them names. Rather, the work is told pretty much entirely in 1st person from the point of view of the protagonist who refers to himself as I, and who refers to the girl as U. This results in the story having a very interesting feel to it, where the readers are really brought into the mind of the protagonist, and wherein things are very slowly revealed to the reader as they’re revealed to him. As for the two main characters, I thought they were both really interesting, and though neither of them is likable at first, with the protagonist seeming really dumb and the girl seeming downright creepy, their minds gets fleshed out over the course of the manga, with a really interesting dynamic being born between the two, and in the end I was very invested in what would happen to U. It is related to that that I felt somewhat of a disappointment, in that I felt the resolution and ending were somewhat disappointing. They weren’t bad in terms of what actually happened, but rather, it was a matter of framing, wherein as previously stated we only see what happens from the protagonist's point of view. However, the protagonist isn’t really involved in it at all with the resolution to U, and hence as the reader doesn’t really see what happens to U either. There is a scene at the complete end dealing with the aftermath that sort of tells you, but it only shows you a glimmer, which is nice in its own way, but especially due to how the reader couldn’t see how things were truly resolved before then, I really wish we got to see more of the aftermath which could provide a bit more closure. The art was pretty good and worked well with the atmosphere.