Rem (レム) is one of the twin maids working for Roswaal L. Mathers in the latter's mansion. Rem is the younger twin sister to Ram. Currently, Rem's name and memories were eaten by Ley Batenkaitos (Sin Archbishop of Gluttony), rendering her in a comatose state.
Rem has medium length sky blue hair that covers her right eye, large light blue eyes, and young features. She also has hair clips towards left side of her hair, flower-shaped ribbon on the same side of her hair, and a maid hairband. She looks nearly identical to her sister apart from her hair, eyes, and ribbon coloring. She usually wears a maid uniform, and since her chest is slightly larger than her sister's, she secretly changes the measurements to hide it.
Rem tends to speak in a superficially polite manner and sometimes acts without thinking. She holds both respect to the point of worship and guilt toward her sister for an incident in the past.
Because of her respect and guilt toward her sister, she used to think of herself as inferior. After Subaru saves her, she falls deeply in love with him, becoming one of his most loyal followers. Rem will stick with him no matter what happens, even if Subaru rejects himself.
In her Oni Form state: Rem's personality drastically changes and becomes that of a mindless killing machine, murdering all without any form of hesitation and can even attack her own allies. Due to its violent nature, she only uses this ability with extreme caution.
Rem has lived with her father, mother and twin sister Ram in an Oni village. It was attacked by the Witch Cult 10 years before the story, following into her sister's hornbeing cut off by Faust. The whole villagegot destroyed along with her parents and the citizens, except for her and Ram.
Ever since, Rem devoloped a strong inferiority complex due to a sense of guilt for her sister's injury, so she made the upmost effort to become as ideal a servant as possible. But even having reached a certain level of perfection, she still has a low level of self-esteem and continues to idolize Ram.
Water Magic: Rem is skilled at Water Magic and Roswaal estimates her skill as being in the lower high. She is able to attack and heal using her magic.
Equipment: Rem wields a Morningstar in combat.
Oni Bloodline (鬼の血族 Oni no Ketsuzoku): As she is an Oni, Rem can enter her Oni Form, manifesting a single white horn on her forehead. The horn increases her physical abilities and acts as a gate which gathers mana from the atmosphere.
- According to the author, Rem's birthday is February 2, the same as her twin sister Ram.
- Rem admits that is superior to her sister in their household chores and cooking.
- Rem is often considered one of the most popular character in the series
- She is also the first character to profess her feelings towards Subaru.
- As pointed out by Subaru, Rem's chest is bigger than Ram's.
- There is a special What-If story, in regards to her and Subaru running away - the two lived happily and even have children.