Esther Rosenthal is a magician and current head of the Rosenthal Family, a 400-year lineage spanning 23 generations dedicated to perfecting necromantic techniques for creating a divine golem with an ideal soul and body. Raised in this tradition, she initially underestimated the gravity of life and death. She inherited the family’s tools, including the perilous artificial souls known as the Evil Spirits of the Numbers. Her physical traits include blonde hair, green eyes, and a mole beneath her left eye. She typically wears a black cloak over a sleeveless white blouse, a red skirt secured by a large belt, black ribbons on her temples, bandages covering her forearms, gloves, black thigh-high socks with a garter belt, leather leg straps, and metal ankle rings. Dark underwear is also noted. After her clothes were soaked during an incident, she temporarily wore a nurse’s uniform. Esther exhibits kindness and politeness toward others, coupled with profound respect for human life and the deceased. She perceives corpses as individuals, not tools, and reacts with anger when they are exploited. The death of her friend Hirumi Hishigata and a failed revival attempt using the Evil Spirit Taowu catalyzed her transformation. Discovering Taowu’s manipulation by her ancestor Isaac and a self-proclaimed demon to advance the family’s goals through atrocities, she renounced the Rosenthal legacy. She blames herself for enabling Hishigata Mikihiko and the organization Disciplinary Action (DA) through her necromantic contributions and resolves to stop them, even at lethal cost. She intended to abandon necromancy entirely after neutralizing the threat. Her background includes a five-year stint in Academy City, where she was deceived into supervising Hishigata’s research team. Her work advanced studies on esper origins and body reinforcement, inadvertently enabling the Coffins corpse-reanimation technology. There, she befriended Hishigata’s sister, Hirumi. Following Hirumi’s death in early August, Esther used Taowu to revive her, only to reanimate the body without restoring true life. Taowu—guided by Isaac—then manipulated Hishigata to orchestrate 10,000 deaths to alter life, death, and reincarnation. During the Necromancer Arc, pursued by DA, Esther hid in Accelerator’s hospital room while searching for Last Order, a DA target linked to the Misaka Network. After escaping captors with Accelerator’s indirect aid, she allied with him against DA and Hishigata. She performed a necromantic ritual on Hitokawa Hasami’s corpse, embedding an artificial soul named Huotou to lay Hitokawa’s spirit to rest. Bound to Esther, Huotou activated in Hitokawa’s body to defend her from DA operatives. Esther later entrusted her cloak to Huotou to preserve Hitokawa’s dignity and relied on its assistance in battles. Post-conflict, she viewed Accelerator as a mentor. In the mobile game *Toaru Majutsu no Index: Imaginary Fest*, Esther returned to Academy City with Huotou to investigate rumors of revived corpses, noting Hitokawa remained deceased. In the comedic spin-off *A Certain Idol Accelerator-sama*, she appeared as an unabashed fan of the idol Accelerator, accompanied by Huotou in Hitokawa’s body. Esther displays unfamiliarity with modern amenities like family-restaurant meals and showers, attributing novel experiences to Academy City’s technology. She shows no concern about states of undress, as when Accelerator encountered her in underwear. In the anime adaptation, she previously referred to herself in the third person.