Sorae Igarashi

Sorae begins her research career as an unusually cold scientist, willing to regard human beings as experimental material. Even Hagire is surprised by how far she initially proposes going for her research.

Motherhood changes her. After Ganta's birth, Sorae discovers that she cannot treat her own child as a specimen, and her growing affection for Shiro subsequently makes the experiments performed on the girl increasingly unbearable to her.

This contradiction defines her later life: she continues participating in the research while simultaneously loving the person being harmed by it and searching for a way to contain what the experiments have created.

Sorae possesses no Branch of Sin. She is a physician and researcher with expertise in medicine, human physiology and experimental treatments designed to enhance immunity.

Her most important technological achievement is the Mother Goose System. Sorae composes a lullaby capable of suppressing the Wretched Egg personality and builds a system that broadcasts it continuously, then seals the mechanism to prevent it from being casually disabled.

She also leaves behind information concerning the system and the research surrounding Shiro, allowing later characters to understand mechanisms created before Deadman Wonderland existed.

Sorae works with Hagire on experimental research requiring a living subject. She originally considers using her unborn child Ganta but cannot proceed after giving birth. Instead, she obtains an albino infant—Shiro—and substitutes her as the experimental subject.

As Shiro grows up alongside Ganta, Sorae becomes emotionally attached to her while continuing the increasingly brutal experiments. The trauma produces the Wretched Egg personality and the Nameless Worm phenomenon, prompting Sorae to create the Mother Goose System to suppress it.

After the Great Tokyo Earthquake, Sorae refuses Hagire's demand for information that would release the Wretched Egg. Overwhelmed by guilt for what she helped do to Shiro, she takes her own life.

Ganta Igarashi is Sorae's biological son. She initially intended him to become an experimental subject but abandoned that plan after developing a maternal attachment to him.

Shiro is Sorae's adopted daughter and experimental subject. Sorae loves her as family while remaining responsible for participating in the experiments that cause Shiro's extreme suffering.

Rinichirou Hagire is Sorae's research colleague. Their goals ultimately diverge when Sorae tries to suppress the Wretched Egg while Hagire wants to continue exploiting it.