[Matrim]

I think the only explanation for Akasaka's wife not being dead is that by episode 15 and The Great Hinamizawa Disaster Hanyuu's powers were a lot stronger so she was able get Rika back in a time at a point before 1978. It's a bit weird that he doesn't appear in the other arcs but then again the main issue in the beginning of this arc is the newfound hope caused by "miracles" so Akasaka deciding on a whim to go on a vacation in Hinamizawa is hardly more likely to happen than Shion, Keiichi and Rena all remembering fragments of other word events. I read Kashikari's analysis but I am not convinced that the "time-jump" can change events further in the past. If it could shouldn't in some of the worlds K1 or Rena not come to live in Hinamizawa for instance?

And as mentioned in the analysis, Irie seems willing to believe that Rika suffers from paranoia which seems to point very strongly indeed that the disease of her and Satoko has to with paranoia and probably with cutting one's own throat as an end result.