Tsukihi Araragi is the supposed younger sister of Koyomi and Karen Araragi and the youngest of the Araragi family. She forms the younger half of the Tsuganoki Second Junior High School's Fire Sisters duo with her sister Karen. Unknown even to herself, she is not human but an offspring of the Shide no Tori, a supernatural entity known as the Dying Bird, granting her a form of immortality similar to a phoenix. She appears as a young girl in her early teens with black hair, dark gray irises, and a distinctive ahoge like her siblings. Tsukihi almost always wears brightly colored yukatas and kimonos of various lengths. Her hair is a constantly shifting style, made possible by its rapid growth—a side effect of her regenerative abilities. A sunny side-up egg-shaped hair clip is always fastened on the left side of her hair. In personality, Tsukihi favors staying indoors, a contrast to her more active sister. Outwardly calm and levelheaded, she possesses a short temper and a hysterical, highly impulsive streak, often acting on emotion without thought for the outcome, such as leaping from a rooftop. She can be airheaded yet occasionally demonstrates startling maturity and sharp insight. She firmly disbelieves in oddities and the supernatural, despite being one. Her identity is deeply intertwined with her relationship with Karen, and she maintains a chaste romance with a boy named Rousokuzawa, whom she says she loves. Her origin lies with the Dying Bird, which, influenced by Seishirou Shishirui’s vampiric aura, infected her mother and reincarnated itself as her child. In elementary school, she befriended Nadeko Sengoku, who gave her the nickname “Rara,” and often played with Karen and Koyomi. She was present when Sodachi Oikura stayed with the Araragis, though she later professed no memory of it. In middle school, she and Karen became the Fire Sisters, engaging in justice-driven acts and earning a reputation for helping others. Her primary ability is immortality. As a Dying Bird, she cannot be killed by injury or illness, regenerating instantly from fatal wounds, though minor injuries heal at a near-human pace. She will, however, die of old age, after which the bird will reincarnate in another child. This immortality also causes her hair to grow at an accelerated rate. Throughout various story arcs, Tsukihi is involved in key events. In Koyomi Vamp, she emails Koyomi about his “journey of self-discovery” and laughs at him when he returns. During Tsubasa Family, she wakes Koyomi with a crowbar, discusses love, and prepares to hunt the monster cat before being stopped by him. The Tsukihi Phoenix arc reveals her true nature when Yotsugi Ononoki and Yozuru Kagenui attack her at home. After having her upper body destroyed by Ononoki’s Unlimited Rulebook, she regenerates immediately. Shinobu later clarifies she is a Dying Bird, not a phoenix. Waking up, she is shocked to learn Koyomi stole her first kiss, leading to a conversation that deepens their bond. In Tsubasa Tiger, she and Karen let Tsubasa Hanekawa stay overnight, and the three share a bath. During Sodachi Lost, she does not recall Sodachi’s stay. In Tsukihi Undo, she skips school and finds Yotsugi Ononoki moving and eating ice cream. She tests if Yotsugi is alive by trying to burn her with oil and a match, accidentally setting herself on fire. Yotsugi saves her and invents a story about being a magical girl. Tsukihi later helps Yotsugi fight a slug tofu, is knocked unconscious, and forgets everything the next day. In Hitagi Honeymoon, her whereabouts are unknown, and she does not attend Koyomi’s wedding. Her catchphrase is “I’m platinum mad,” sometimes translated as “dagnabbit mad.” Trivia notes her name means “moon fire” or “Monday and Tuesday,” and both she and Karen have the kanji for fire in their names. Her surname, Araragi, contains kanji for “pandering,” “good” (repeated), and “tree.”