Nameless Worm

Nameless Worm are the parasitic worms that enhabit the bodies of the Deadmen.

History
The worms were originally created by Sorae Igarashi and Hagire Rinichirō. Together, they researched different ways of heightening a person's immune abilities. The pair used several guinea pigs including Shiro for these experiments. Their existence was determined to be a byproduct of the pair's research.

Due to the Great Tokyo Earthquake, the worms were spread throughout Tokyo.

Effects of the Worms
Main Article (Deadmen)

Once inside a human, the Nameless Worm integrates with the body, altering the subject permanently. When this happens, the person is then refered to as a Deadman.

Most Deadmen were infected during the Great Tokyo Earthquake, however, there are exceptions, namely Ganta Igarasi, whom was infected by the Wretched Egg, during the Nagano School Massacre.

Powers
Main Article (Branch of Sin)

The Branch of Sin (罪の枝, Tsumi no Eda) is the ability to control and freely move your own blood. The Branch of Sin is mostly used as a weapon and can form into various objects. This power was created by the Nameless Worm carried by the Red Diamond. Different Deadmen have different powers but it's unclear what decides their unique manifestations of their Deadman powers.

Synthetic Copies
Main Article (Forgery)

Tsunenaga Tamaki was able create artifical Deadmen called Forgeries. They posess the powers of Deadman as well as a poison (carried in their Branch of Sin) designed to give them an advantage Deadmen. The copies are forced to wear masks that not only induce brainwashing effects, but cause the wearer to remain in a heightened, euphoric state.

Their elite troops are called Complete Forgeries.

Removal
Main Article (Worm Eater)

Worm Eater is a device that instantly oxidizes the Nameless Worm residing in the Branch of Sin. With the Nameless Worm gone, a Deadman's blood becomes useless, making him unable to attack.

The Worm Eater was invented by Tsunenaga Tamaki and was given to the Undertakers. It has been effective against every Branch of Sin, except Ganta's Ganbare Gun and the Wretched Egg's Branch of Sin. It seems that these special Branches of Sin are immune to the Worm Eater.

The only way to counter Worm Eater is to attack with the speed of sound, breaking the sound barrier.