Okay, I know you can't really expect a psycho serial murderer to actually think rationally, but... His whole purification theory makes no sense at all? If murdering someone is what makes you a monster, how is murdering more people going to turn you back to a human? Like, his twisted idea of drinking "pure" blood would make some sense if, say, someone else procured the blood and offered it to him? But him killing more people in the process of purifying himself is self-contradictory.
This depends on whether he makes a distinction between one murder and one hundred murders. One could take the stance that, one or one hundred, a murderer is a murderer. This would mean that you don't need any more purification for one hundred murders than one murder.
Sure, but. He claimed that it takes two years for all the cells in your body to be replaced, didn't he? And the plan was to consume "pure" people in the meantime, so that his renewed body would be human again. If we accept that the "pure" blood cleanses his body, then wouldn't it be corrupted again with the next murder? Even if the number of victims doesn't play a role in this, time absolutely does —he did bring it up on his own, after all. What I'm trying to say is, following his "logic" of replacing his impure body cells with human ones, the two-year time frame should be reset each time he murders another person.
I liked how chapter 28 was constructed, with the reveal that the serial killer was only responsible for a single death in the Kurosu family shown parallel to Natsuki (hopefully not) getting caught up in Tokiko's curse(?)
I really hope she doesn't die, though.