Mary Bult serves as a member of the Imperial Diet in the Wahrheit Empire. She champions legislation to increase the size of the imperial army and ban civilian possession of heavy weapons. Later, she coordinates with imperial army officials during a meeting, urging joint Diet-military action to eradicate the smuggling organization Headkeeper during their major operation in the capital.

Secretly, Mary Bult is implicated in clandestine human experiments conducted at a shuttered mental institution. Overseen by Professor Radovaud, these experiments transform people into monstrous entities. Elfriede, an operative of Headkeeper, infiltrates the facility, unearths Bult's connection to the project, and is captured. Elfriede subsequently undergoes transformation into a monster as part of these experiments.