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 Igarashi, who 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 be formed into various objects. This power was created by the Nameless Worm carried by the Red Diamond. Different Deadmen have different powers. It's unclear what decides their unique manifestations of their Deadman powers, whether it's Deadmen's personalities, their genetic and biological differences or if it's a unique power on its own.

Certain Branches of Sin have been developed far enough to achieve the speed of sound by breaking the sound barrier. The only Deadmen to achieve this are Ganta, Senji and Minatsuki (exclusive to Anime).

It was shown that Branches of Sin can evolve over time, such as Ganta's Ganbare gun and Senji's unnamed evolved Crow Claw. The evolution itself has occurred due to their strong will to live and high determination, eventually leading to their new powers. Evolved versions don't stray too far from their original powers and appearance, as they only intend to boost them with speed and strength. Patterned, black lines (shiny red-pink in the Anime) appear on Deadmen when using the evolved Branch of Sin, usually from part of their body where they manifest their Branch of Sin, all the way to their face. Their appearance is distinct for every Deadman, from straight patters to curly lines.

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 over 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 for the ones that evolved, such as Ganta's Ganbare Gun and the original Branch of Sin of the Wretched Egg.

The only way to counter a Worm Eater with a regular Branch of Sin is to attack with the speed of sound, breaking the sound barrier, like Senji's Invisible Black and Ganta's Supersonic Ganta Gun.