Inner Demon
Inner Demon

The Inner Demon (最深部鬼) is a special NPC located at the very end of the Rust Corridor. She looks like Sabitsuki, but leaks blood and has horns.

The player has to kill her to be able to exit her room. She takes about five hits from Rust before she dies. After she is killed, Sabitsuki wakes up in her room and can leave it to see the Rust Ending.



  • Rust's most damaged form seems to only slightly resemble a demon, unlike the Inner Demon, who has defined horns and is less damaged, despite the leaking blood.


  • It is possible that she represents Sabitsuki's core.
  • Alternatively, she might represent the source of whatever ailment Sabitsuki has.