Masae Tōdō, the underworld figure known as "Bearslayer," commands a criminal empire spanning illicit enterprises. Her operations include controlling children's homes and exploiting the orphans within them for profit. Tōdō forces individuals, like the orphan Misa, to labor under her to settle fabricated debts incurred by these institutions.

A ruthless manipulator, Tōdō employs threats and hostages to achieve her ends. She leverages the protagonist into stealing the legendary aquamarine gem, the Mermaid's Scale, during a secret underground auction. Her ambition drives her to acquire the stone, though her precise plans for its value or power remain undisclosed.

Shortly after securing the gemstone, Tōdō meets her end when Himuro's enforcer, Kageura, murders her in cold blood. During the attack, she attempts to shield herself using Misa, resulting in both being impaled together by Kageura's weapon. Her early demise acts as a catalyst, propelling the narrative forward rather than establishing her as a lasting antagonist.

Tōdō's background intertwines with the broader conflict surrounding the Mermaid's Scale and the quest for immortality. Her exploitation of Misa, whose unique healing ability connects to the gemstone's mythology, underscores her role in perpetuating cycles of abuse. Her criminal network, including the children's homes, sets the stage for introducing other key figures like Maki, a 14-year-old orphan aspiring to be a thief. Tōdō's actions directly fuel the central mystery concerning the gemstone's true power and the Yao Bikuni legend. Her documented presence is confined to this specific narrative.