Shiro

Shiro is a childhood-friend of Ganta and the original Deadman - The Wretched Egg.

Personality
Shiro is a bubbly, happy girl that seems to be a klutz. She also has a lot of energy, although her mind cannot understand much. While she doesn't fully understand Deadman Wonderland, she knows how to help Ganta and only wants his happiness. She is incredibly strong, however dense she is, and uses her strength to help Ganta as much as possible. Eventually she managed to force her body into using her Branch of Sin, which appeared to be similar to Ganta's "Ganta Gun".

The Wretched Egg, on the other hand, is almost the complete opposite. It doesn't speak much, if at all. To it, killing is a fun game, and during this game it wears a Cheshire grin. Its powers are unrivaled and were the cause of the large earthquake that hit Tokyo so long ago. Later on it is revealed that its wounds heal at a miraculous rate, making it seemingly impossible to kill.

History
Before the birth of the Wretched Egg, Ganta and Shiro played quite often, sharing a common admiration of Ace Man, a Megaman-like cartoon hero. Shiro was a test-subject of Ganta's mother, so they saw each other often. She got along well, but one time, when Shiro was in grave pain because of the constant injections, they once bickered so violently that Ganta took his toys and ran away from the hospital. Soon after, he came face-to-face with a rabid, vile dog. Ganta dropped to his knees in fear and called for Ace Man to save him. Suddenly, Shiro appeared in between Ganta and the dog, saving his life. After this, Ganta and Shiro were even more close.

Wretched Egg
Shiro's split personality the Wretched Egg, also known as The Red Man. The Wretched Egg was created by Ganta's mother, Sorae Igarashi. The Red Man is the cause of the Great Tokyo Earthquake ten years ago and he is also responsible for the Nagano school massacre. The only way to keep him under control, is the Mother Goose System.

The Red Man is the opposite of Shiro. He is sadistic, doesn't care about friends and he doesn't like candy (and Shiro adores candy). The most obvious difference is that Shiro is naïve and sweet while the Red Man is just plain evil.

Branch of Sin
Shiro: As Shiro, she has shown minimal control of her Branch of Sin and has been able to use it in combat only once. She first discovered her powers when Ganta and Senji were discussing their Branches of Sin. She used it to fight for the first time in Ganta's battle with Shishito Madoka, where she saved Ganta when he was about to get killed.

Wretched Egg: As the Wretched Egg, her powers are unmatched even by the strongest of opponents while her powers were restrained by the Mother Goose System. She has been shown to massacre dozens of people by creating a whip of blood that can destroy parts of the body instantly. His Branch of Sin also resembles a hurricane. While unrestrained, she was powerful enough to cause the Great Tokyo Earthquake that submerged a large area of Tokyo.

Trivia

 * Shiro's name means white in Japanese.