Character development of Sailor Mars

Rei is not named in the original proposal for a hypothetical Codename: Sailor V anime, but an identical character in miko clothing is present, named Miyabi Yoruno. Creator Naoko Takeuchi confirms that this character eventually became Rei, and writes that her role as a shrine maiden was inspired by Takeuchi's own experience working as a miko for Shiba Daijongu Shrine while she was in college. She also states that she was frequently "hit on" by the shrine's patrons, a source of annoyance that carries over into the character's life.

Hikawa Shrine, where Rei lives and works, is based on the real-life Hikawa Shrines, one of which is in Azabu Jūban, where the story is set. The kanji for "ice" in the original name (氷川神社) is replaced with the kanji for "fire"—a reflection of Rei's element.

Sailor Mars's original costume design, like the others', was fully unique. It featured an alternate bow, double shoulder-guards, plate-armor, elaborate jewelry, and a gold-rimmed mask. Her trademark high-heeled shoes were already present, as well. Later, Takeuchi was surprised by these sketches and stated that she did not remember drawing them. In an intermediate design, the pendant that sat at her waist in the early manga was also intended to be worn as a necklace in her civilian form. Hitoshi Doi states that Kunihiko Ikuhara was responsible for much of Rei's changed personality in the anime.

The kanji of Rei's surname translate as "fire" (火 hi) and "field" or "civilian" (野 no). Her given name is in kantakana rei (レイ) and therefore difficult to translate. Possible meanings include "spirit" (霊), "companion" (儷), "cool" (冷), and "zero" (零), with the first being most commonly assumed. Because katakana is the alphabet usually used for foreign loanwords, it may also be intended as a Western name, such as Raye or Rae. In the Chinese versions of the series (anime and manga), Rei's name is written with the character "麗", which carries the same phonetic as "Rei", but means "beauty." Regardless, the entire name is structured as a pun , as the syllable "no" indicates a possesive, so that her name can also be understood as "Rei of Fire." Her prototypical name, Yoruno Miyabi (夜野みやび), means "Elegance of Night." Rei's name (レイ 野の Rei Hino) translated could act as a pun as "Ray of Fire". This would be the most literal translation of her name.

In an early DiC promotional tape that advertised the English-dubbed series to television stations, Rei was called Dana.

It has been noted that her outfit as Sailor Mars echoes the colors of her miko robes, and she is the character that is most tied into tradition