Mutsumi Tendo forms one-third of a homunculus triplet unit engineered for the Sefiro Fiore Nagataki Branch, alongside indistinguishable sisters Itsuki and Nanase. These triplets jointly embody the "Wheel of Fortune" from the Elemental Tarot, a card signifying fortune fluctuations and critical turning points in its upright position, yet representing accidents and deteriorating conditions when reversed. Their synchronized operations encompass managing dimensional teleportation systems, coordinating field deployment logistics, and conducting specialized research to aid Tarot wielders during Daemonia suppression missions.

All three sisters share identical physical traits: white hair, red eyes, a height of 106cm, and childlike features. They consistently wear shrine maiden outfits adorned with hair bells. Functioning as a collective entity, they exhibit perfectly harmonized speech and task execution without individual distinction. As artificial constructs, they possess no personal histories, familial ties, or character development beyond programmed directives. Mutsumi’s existence remains inseparably intertwined with her sisters across all documented media, including light novels and manga adaptations, with no exploration of her as an independent entity. Under the supervision of Etia Visconti and Ariel Westcott, the triplets maintain a neutral and methodical efficiency in all duties.