They get a little competition and suddenly SA sets a speed record? So proud of you all! *applause* Then again, this chapter didn't have much to redraw and that's always the slowest part.
Yeah, clearly Suika snapped not so long ago. Obviously she's still out there, still unhinged, and still probably in line to be endgame final boss, but now there's more questions than answers...
Seiko not remembering anything about their old neighbors is probably Suika's doing...by erasing everyone's memories of them, when she killed them. It's consistent with Seiko's feelings that they all left at once—obviously Suika showed up one day, burned them all out, but skipped the Yoshidas because barrier.
Shamiko needs to get a clue and just confess already.