This certainly could have been a 40 chapter thriller with a much different ending, but it makes perfect sense for the story to have progressed as it did. The themes and motifs were well done, and the diary is fairly rare in manga to portray the passage of time and portray a character's thoughts and feelings over time. Although, for that reason it does sort of feel like a light novel adapted into Manga without much clear visual direction. For that reason, I can only rate it an 7/10 even though I liked all of the characters and the art and everything else. The endingwas masterfully done, though, and is rather well thought out.