Anno encountered difficulties writing the character, not feeling "particularly interested" nor relating to her, but he thought of her as a representation of his unconscious mind. He also said that during production he forgot about her existence, giving her just a marginal space. In the fifth episode, explicitly dedicated to her character, Rei speaks seven lines and fifty-two words in the whole installment. Her storyline also changed. In the second draft of the scenario for the first episode, it was planned for Rei to rescue Shinji with an Eva. According to Neon Genesis Evangelion assistant director Kazuya Tsurumaki, the tentative plot would have given a valid reason for Shinji to choose to get on 01, thinking that Rei was hurt because of him, but the storyline was changed. A final scenario, in which Rei is injured during a botched Eva-00 test, was then considered. Moreover, the idea of Gendo's glasses being broken during the test was provided by Yoshiyuki Sadamoto, the character designer of the series. While the scene where Shinji enters Rei's room was done in the style of Neon Genesis Evangelion, the scene where Rei is described as a normal girl was done in the style of Junichi Sato, who previously worked on the Sailor Moon series. In the meal scene between Misato Katsuragi, Ritsuko Akagi, and Shinji, Misato was represented taking inspiration from Usagi Tsukino, the protagonist of Sailor Moon. In the same scene, staff inserted graphic and humorous symbols on the characters' heads taking inspiration from the shōjo mangas and Sailor Moon. Furthermore, Sato tried to represent the scene in which Shinji is discovered in Rei's room by imitating the style of Leiji Matsumoto. He also wanted to add more details to the description of daily life, but Anno thought it would be excessive. Anno only gave the instruction to represent Rei's room as a "bleak room", and to represent it Akio Satsukawa was inspired by a flat he saw when he worked as a part-time plumber. It was easy for Satsukawa to write "Rei I", and the final product did not differ much from the initial draft he wrote. Jin Yamanoi and Yuko Miyamura voiced the unnamed Nerv technical operators in the episode, Koichi Nagano and Hiro Yuki played two boys from Shinji's school, while Megumi Hayashibara, Rei's Japanese voice actress, sang a version of Fly Me to the Moon used as the ending theme.