From the conversation between Yayoi and Sachiko, we can assume it was the same black entities that herald the news of impending death. The very same one that appeared in F Park Ghost Granny case, they came from a crack in the sky(netherworld).Is that the same entity that harassed the park ghost woman?
Yep. The next physical volume was scheduled to come out in May/June. Can't remember though which arc exactly, probably somewhere around Volume 12, the arc of Shishimura and Marbas.I don’t read Japanese, but does the last page say something about the next chapter coming in June?