The Sanekui Mushi (核喰蟲, lit. core-devouring mushi) is a large, dark shadow-like Mushi who attracts and feeds on other mushi despite not being near the river of light. There seems to be some indication that this mushi is connected with the forbidden mushi that the Karibusa and Minai families are sworn to fight.
The Sanekui Mushi appear as a massive black cloud that looks like a hand.
The Sanekui Mushi is defeated by a white artificially created kouki distillate mushi which is implanted in a soulless human. When attacked, it emerges to consume the darkness, leaving an empty human shell behind.