"Sis" is a nurse who was taking care of Five in the human world.
Sis has strawberry blonde hair tied into a bun. Underneath her lab coat attire, she wears a green sweater, purple miniskirt, black leggings and purple loafers. She wears a pair of round glasses. Her eyes are light green.
She enjoys taking care of Five and reading her stories, though she dislikes the grim endings of those stories, and chooses to make her own. She displays a more loose, carefree side when throwing a birthday party for Five. She's also a bit of an alcoholic.
When Five was very young and sickly, she was transported to a human hospital by Sis. There, Sis took care of her and her condition gradually improved. She played with Five every day and read her stories that Five still recalls with great detail. Sis seemed to dislike the ongoing royal disputes between princess Ruta and prince Suvillan III at the time, and tried to distract Five from it as much as she could.
At one point, Sis arranged a birthday party for Five with the presence of Solis and Lune. After Five's birthday, Sis, along with everyone else were gone for unknown reasons and the hospital was in ruin. It is unknown what the current status of Sis is.
- Sis is associated with red spider lillies. Spider lillies symbolize goodbyes, people parting ways for good, abandonment, and death.
- She's not the only female blonde human to try altering the ending of a story.