Wraith Sisters

The wraith sisters are supporting main characters in Maou ni Natta node...

Rei (レイ), Rui (ルイ), and Rou (ロー, Lowe) are the names of the trio of sisters listed from oldest to youngest. Yuki summoned them after the creation of his castle, Luan Fionell Castle. They are in charge of defense and haunt the castle to scare off intruders.

Wraiths are born from basking in a poor souls dying wish and these wraith sisters lack this quality. The wraith sisters were summoned at the same time and they love pranks.

Appearance
The wraith sisters appear to be 3-4 year old children with translucent bodies. Because they are incorporeal, Yuki gave them dolls to possess so they could interact with everyone.

Personality
The wraith sisters are childish and like to play pranks. They were terrified of Lefi at first but have grown to like her.

Rei acts as a big sister should. She is smart and usually has everything planned out in her head before hand. When she plays pranks, she usually instigates her sisters to support her endeavors.

Rui is a stubborn girl. She is the most prideful and honest of the sisters. Her sisters' shenanigans often cause her to panic.

Rou is relatively quiet and reserved. She is also the most mischievous of the sisters and her pranks often leave her sisters shocked stiff.

History
The wraith sisters were summoned and only Yuki knew about them until they scared Nell.

The wraith sisters spooked the hero when she invaded Luan Fionell Castle. Their lack of malice and desire to kill prevented Nell's detection skill from noticing them.

Because of the lack of intruders, the wraith sisters often play with the younger residents of Yuki's dungeon while possessing dolls.

Abilities
Each sister has their own special ability.

Rei has telekinesis.

Rui has illusion magic that affects the senses; her magic is abnormally powerful as it has physical substance.

Rou has mind magic; her spells are specialized to alter the target’s perception of reality by manipulating their senses.

Trivia

 * Yuki summoned them alone without telling Lefi.
 * They are the 3rd-5th monsters Yuki summoned.
 * They have a lot of dolls (their clothes) they can posses when they need a physical body.