Rumia

"Is that so~?"

- Rumia

Rumiais a youkai that can manipulate the darkness, but judging from her Embodiment of Scarlet Devil appearance, she is only powerful enough to make it seem like late evening. Apparently she is quite simple-minded, but isn't featured in enough conversations for details about her personality to be revealed. Rumia's hair ribbon is actually an amulet. She can't touch it, so she can't take it off.

In the events of Embodiment of Scarlet Devil, she's attacked by the heroines for no reason (probably just as a general warmup), and has nothing to do with the main story.

According to comments about her in the Bunbunmaru Newspaper and in Perfect Memento it seems that she's constantly surrounded by a mass/blob of darkness at all times except during the new moon, and so is rarely actually seen in person. Despite her innocent appearance, she eats humans.

Appearance
Red eyes, short blond hair. Wears a black vest and skirt, and white blouse. A small red amulet is tied to the left side of her hair, making it look like a ribbon.

Relationships

 * Cirno (Known)

Fan speculation
It is often speculated among fans that the amulet Rumia cannot take off is actually a seal keeping vast power in check. Many fanworks depict the seal being removed somehow, allowing Rumia to transform into a much more powerful entity named EX Rumia (for Extra). Rumia's attributes in this form are typically a pair of large feathered black wings and a sword, and her power over darkness ranges from vast to godlike. She is almost always depicted as malevolent.