The Onigo (鬼子) are black-haired girls found throughout the flow. They appear to wear blue dresses and their faces are never seen.

One is found lying on the ground in the Sunset area, with children surrounding her body. Another, the pregnant one, is seen in the past version of the Back Ward. Several of them are located in the Visceral World and a single Onigo is in the Womb Maze, Sabitsuki gets the Viscera effect by interacting with her.

The Childbirth event can be randomly triggered in the Reverse Apartments, which leads to a secluded part of the Visceral World with many Onigo. Sabitsuki has to murder her way through this room to get to the actual event, where a giant Onigo has viscera splitting out of her stomach.

When they are approached by Rust, the Onigo quickly decay and die.

Some Onigo can be seen in the Outside and Rust endings.


  • The Onigo are named after the switches that control the Childbirth event. Another name associated with them is simply Oni (鬼), "demon".
  • Onigo (鬼子) can be translated as "child born with teeth​", "child which does not resemble its parents", or "badly-behaved child".


  • It is speculated that these girls represent some kind of cancer, since they seem to collect in a fleshy area resembling the inside of a body.
  • Alternatively, they might represent Sabitsuki's immune system, since they start dying at the same time the Fetuses overrun the flow and start dealing actual damage. It is speculated that the presence of Onigo early in the game was preventing them from leaving the Womb Maze.