Rei Hino is Sailor Mars, Guardian of Mars wielding the element of fire. Her background reveals she is the only child of politician Takashi Hino and Risa Hino, who died when Rei was young. This loss, coupled with her father's emotional neglect and career prioritization, fueled resentment toward him and a general distrust of men. She subsequently moved to Tokyo's Hikawa Shrine to live with her grandfather, the head priest. There, she trained as a miko, developing psychic abilities like precognition, pyromancy, and spirit communication, though these powers were sometimes unreliable. She befriended two crows named Phobos and Deimos, after the moons of Mars, who serve as her companions. Rei attends the elite T*A Private Girls' Academy, a Catholic school. Her personality varies significantly across adaptations. The manga and *Sailor Moon Crystal* depict her as stoic, traditional, and reserved, expressing contempt for modern romance due to her father's influence. The manga side story *Casablanca Memories* explores a brief romantic interest in her father's secretary, Kaidou, ending in disappointment with his arranged marriage. Conversely, the 1990s anime portrays her as hot-headed, ambitious, and occasionally boy-crazy, with career aspirations in singing or modeling. This version includes a short-lived romantic relationship with Mamoru Chiba (Tuxedo Mask) and a gradual bond with Yuuichirou Kumada, her grandfather's apprentice. The live-action series (*Pretty Guardian Sailor Moon*) aligns more closely with the manga, emphasizing her initial aloofness and eventual loyalty to the Sailor Guardians. As Sailor Mars, Rei fights using fire-based attacks and spiritual techniques. Her initial abilities include *Akuryo Taisan* (exorcism using ofuda charms), *Fire Soul* (a fireball projectile), and *Burning Mandala* (rings of fire). Obtaining the Mars Crystal upgrades her powers, unlocking *Mars Flame Sniper*, where she conjures a fiery bow and arrow reflecting her miko archery skills. Her costume evolves with each power-up: the base form features a red and purple sailor fuku with star earrings and a tiara; the Super form adds a heart-shaped brooch, translucent shoulder pads, and a lengthened back bow; the Eternal form (achieved in the *Dream* arc and depicted in *Sailor Moon Eternal* during the battle against Queen Nehelenia) includes a V-shaped choker, layered skirt, white knee-high boots with star accents, and a star-shaped tiara gem. This Eternal transformation occurs when Rei and the other Guardians awaken their Sailor Crystals to become Eternal Sailor Guardians. Rei's relationships with fellow Sailor Guardians are pivotal. While she frequently clashes with Usagi Tsukino (Sailor Moon) in the anime over leadership and personality, she demonstrates fierce loyalty, especially in crises. The manga and live-action series show a closer bond with Minako Aino (Sailor Venus), with Rei often serving as secondary leader. Her character development consistently highlights dedication to protecting Earth and the Solar System, embracing her spiritual role, and accepting her Guardian destiny, including a vow of chastity in her past life as Princess Mars of the Moon Kingdom. The side story *Parallel Sailor Moon* depicts a potential future where she runs a calligraphy school at Hikawa Shrine and has a daughter named Rei with an unnamed husband who is a Shinto priest.