The stalker is a creepy girl who takes on some relevancy with the whole anime "little sister" nonsense. While this stalker still always felt dangerous to me and somewhat unpredictable, she always had this overly-dramatic sense to her and that she was always moderately limited to her humanity when she went about killing people. At times she would take upon supernatural elements, but never did this carry over into her killings. This made her feel more like a crazy little girl than a monster. There wasn't much mystery to this stalker girl beyond learning her patterns, and while there was some intrigue in learning more about her later on - I never really felt intrigued about her as a character as I don't really see a logical set of scenarios leading to such a personality, I would've more assumed it was some mental condition.
While the story felt dangerous for the victimized characters, the story never really felt creepy or off-putting. The way in which the girl acted seemed as if she tried to be creepy instead of being inherently creepy, but that may just be how I unfortunately came to interpreting it. But due to that, it was hard to really enjoy this manga. It was interesting though in that the story really does seem to want to bring in this monster as a character, with interactions and all. You don't exactly have those stupid moments in horror flicks where everyone splits up and the monster goes one-by-one either (note the "exactly"), but you get some moments with multiple people being there as the monster is clearly visible and interacts. It made for some quite interesting moments, but the moments were never much beyond interesting in terms of being scary. I'm not one who can really get creeped out by something that we have so much knowledge about. If I know the limitations of my predator, I will work against those limitations and not just continue to treat it as an unpredictable beast. I'm not saying that nudging to the cast though, as I felt the main character (at least) acted reasonable to the whole situation. I personally couldn't connect to how he treated the monster in that it felt pretty clear that treating the monster in such a way would back-fire, but he did seem to kinda get the picture later on. But, overall, Ibitsu isn't unique and I would personally be even more creeped out if I just went to some creepy-pasta urban legend threads than seeing this urban legend play out before my eyes. The legend they use here is interesting and may very much creep out those who love their imotos, but I feel those who need something a bit more to be creeped out might prefer to look elsewhere.
A better version of this (while being more of a thriller than a horror): http://myanimelist.net/manga/977/Zashiki_Onna
