The Worm Eater was invented by Tsunenaga Tamaki and was given to the Undertakers. After Scar Chain's prison break, Karako Koshio smuggled Undertakers' weapons out of the prison and handed them over to Ekō Kaidō, in cooperation with Makina. He had a university lab research the Worm Eater and later planted it in a sword that was then smuggled into Deadman Wonderland. The sword was given to Makina who used it as a weapon against the Forgeries.
The only way to get around the Worm Eater, is to attack with the speed of sound, breaking the sound barrier or destroying it with physical force. Known Branches of Sin that can do this are Senji's Invisible Black and Ganta's Supersonic Ganta Gun.
- Azuma Genkaku: in the skull on his necklace
- Hibana Daida: embedded in her weapon
- Other Undertaker foot soldiers: in their weapons, that varies from regular swords to katana's, saw and guns
- Makina: embedded in her sword
- Yō Takami: In Operation Mother-Gizmo Reinforcement, he steals and uses Makina's sword.