Helena von Bähbem is the niece of Ernst von Bähbem, the head of the powerful Bähbem Foundation, and also serves as his personal secretary. As the second in command within the foundation, she acts as an envoy, most notably delivering the artifact known as the Vermillion to Nirai-Kanai. Helena shares a history with Makoto Isshiki and Itsuki Kisaragi, having known them since childhood.

In terms of personality, Helena is defined by a deep-seated jealousy and a sense of unfulfilled destiny. As a child, she dabbled in witchcraft and was identified as a potential Instrumentalist, an individual capable of operating mecha and "tuning" the world. However, she passed the ideal age for awakening these abilities without ever realizing her potential. Consequently, she harbors significant resentment toward those like Quon Kisaragi who might succeed in the act of tuning the world, a task that remains just out of her own reach.

Her role in the story is closely tied to the machinations of her uncle. Her personal journey culminates in a dramatic and unsettling development: she ultimately allows Ernst von Bähbem to take over her body. This act represents the final abandonment of her own identity and ambitions, as she becomes a vessel for the foundation's greater plans. Her key relationships are therefore primarily functional, defined by her service to her uncle and her envious observation of younger, more promising Instrumentalists. Her notable abilities include her early training in witchcraft and her latent, though unrealized, potential as an Instrumentalist.