TV-Series
Description
Kurumi Tokisaki, codenamed Nightmare, transitions from major antagonist to a complex figure. Originally an ordinary human from a wealthy family, she was saved from a monster by Mio Takamiya, who claimed to be an "ally of justice." Mio granted Kurumi the Sephira Crystal containing Zafkiel, unknowingly transforming her into a Spirit. Kurumi then hunted over fifty Spirits alongside Mio. Discovering one victim was her best friend Sawa drove Kurumi to near Inversion, halted only by using her Fourth Bullet Dalet to rewind time. Mio then revealed herself as the First Spirit, explaining her plan to refine Sephira Crystals by bonding them to humans and killing the hosts. Kurumi awoke later in a Spacequake crater with only knowledge of her Angel's functions. Using her Tenth Bullet Yud restored her memories, leading her to swear to alter the past using the Twelfth Bullet.

Her core motivation is to travel back thirty years and kill the First Spirit, preventing the first Spacequake and emergence of Spirits. This requires vast spiritual energy, leading her to target Shido Itsuka, whose body holds sealed Spirit powers. She transfers into Shido's class at Raizen High School specifically to consume him. Kurumi views humans as sources of "time" to extend her own lifespan and power her abilities, as using her powers drains her life force. She absorbs others' lifespans, preferring younger individuals for their remaining years. Her actions result in over 10,000 human deaths (excluding Spacequake victims), earning her the title "Worst Spirit."

Her Angel, Zafkiel, is a clock-type weapon granting time manipulation and shadow control. She summons two guns—a musket and a flintlock—positioned like clock hands to fire temporal bullets. Key bullets include Aleph (acceleration), Bet (deceleration), Dalet (healing via time rewind), Zayin (freezing targets), Yud (memory viewing), and Yud Bet (time travel). Her signature technique, City of Devouring Time, uses shadows to drain victims' lifespans. These shadows also create clones of her past selves; these clones are less powerful and may exhibit traits she has outgrown, like chūnibyō tendencies. They act independently but share her core memories and goals. She can also summon Spacequakes at will.

Personality-wise, Kurumi presents a dichotomy: outwardly polite and refined, yet inwardly ruthless and manipulative. She adopts the façade of an innocent schoolgirl to infiltrate social settings, like enrolling at Raizen High. Beneath this, she displays psychotic tendencies, including maniacal laughter, and views people primarily as sustenance. Her actions reflect a twisted sense of justice, exclusively targeting individuals engaged in harmful acts like would-be rapists or animal abusers—exemplified when she killed four men tormenting a kitten. Her affection for small animals contrasts her brutality, hinting at residual humanity. She rejects being labeled "kind," threatening an entire school to dissuade Shido from redeeming her. Her interactions with Shido evolve from predatory to occasionally cooperative, such as aiding him against Miku Izayoi or DEM Industries, though always with self-serving motives like locating the imprisoned Second Spirit.

A pivotal moment involves Origami Tobiichi, whom Kurumi sends five years into the past using Yud Bet. Origami aims to kill the Spirit responsible for her parents' death, but this act inadvertently causes the tragedy, triggering Origami's Inversion. Later, after achieving her goals or facing consequences, Kurumi's powers are sealed by Shido. She enrolls at Saito University and establishes the Tokisaki Detective Agency, marking a departure from violence while retaining strategic acumen.

Her design features long black hair, often in uneven twin tails resembling clock hands in Spirit form, and a crimson-black Gothic Lolita Astral Dress called Elohim. Her left eye manifests as a golden clock face showing her remaining lifespan; her right eye is red. After absorbing Nia's Sephira Crystal, her dress incorporates cross motifs. In human form, both eyes appear normal, and she wears practical attire like school uniforms or casual wear.