Undertakers

The Undertakers (墓守, Andāteikā) are a special force created by Tsunenaga Tamaki. They are the worst criminals who survived the "special correctional program". They are also called the Anti-Deadmen Corps. The Undertakers possess technology called the Worm Eater that allows them to nullify a Deadman's Branch of Sin ability.

Some time in the past, Genkaku killed Nagi's wife and this caused Nagi to go insane and massacre 22 Undertakers. Since then, Genkaku has continuously tried to get Nagi to join the Undertakers. The Undertakers played a big part in Scar Chain's mass prison break, as they were Scar Chain's direct enemies.

Trivia
The foot soldiers of the undertakers are shown to be not only murderous but completly immoral as shown when they attempted to gangrape Shiro and Karako when they were both captured by Azuma.