In the manga, Rei is a somewhat snotty but sophisticated Shinto priestess. She is hesitant at first to accept her role as a sailor soldier but fights loyally alongside the soldiers to protect her princess and Earth. She is the ideal Japanese woman - beautiful, intelligent and reserved. Her personality in the manga differs much from the anime; she does not have the temper her anime self has.
In the manga, she is close to Minako Aino more than in the anime.
In the anime, Rei is more hot-tempered and less icy. She fights with Usagi Tsukino a lot because she worries for her safety and that of the planet they are sworn to protect. Rei often disapproves of Usagi's slacker attitude. Later, Rei admits herself that she was wrong about Usagi as a Sailor Senshi Leader. Despite their fights, they are extremely close friends who love each other dearly. She lives with her grandfather at Hikawa Shrine. She is not only hot-headed but is skilled in the art of fire reading, and has prophetic dreams.