Rumia falls into the weaker category of youkai, but she possesses an ability that makes her surroundings dark whether it is night or day.

The darkness this youkai emits is a magical darkness that renders even torchlight useless, and humans that wander into this darkness have their field of vision reduce to almost nothing.

It is simple to drag people into the darkness and attack them, but she does not move with a group of other youkai, which is a relief.

Her appearance is that of a young girl with red eyes and a red ribbon in her blond hair. It is said that she wears dark clothes to blend in with the darkness, but since it is always dark around her this is difficult to confirm.

Perhaps because she is known as a monster of darkness and is normally feared, people who have directly seen her form discover a young girl and are overcome with relief.

It is possible that she covers herself in darkness to hide her appearance.

Also, it is said that her ability to manipulate darkness is only a supporting ability, and that she uses pure power to attack humans.

Since she looks like what she looks like you cannot tell if she is really strong or not, but it isn't possible to fight against her in the darkness.

Not being able to see a way out is frightening.

"I saw a large blob of darkness heading towards the forest. It was scary." (Hikozaemon)

The large blob of darkness is believed to be this youkai.

You must not approach it.

"Then the large clump of darkness bumped into a tree and looked like it stopped moving for a bit, but it came towards me so I ran away." (Hikozaemon)

She most likely bumped into a tree.

Perhaps she cannot see outside the darkness either (*1).

"I was too slow in escaping and got caught in the darkness, but I didn't encounter the youkai and slipped right through." (Anonymous)

Even if a human enters the darkness, the youkai inside might not notice.

If that is the case, she most likely cannot see in the darkness she produces (*2).

1: Imagining that, the blob of darkness suddenly becomes amusing.

2: Perhaps she really is stupid.

Since a human's power can't compare to a youkai's in the first place, it would be impossible to put up a fight within darkness that renders even torchlight useless.

The best way to deal with this would be to not enter the darkness unless you are very confident in your abilities.

You should also avoid visiting places where the moonlight doesn't shine at night.

Rumia may be lurking there.

Rarely, there are cases of people who have run into Rumia while she was not emitting darkness.

This was on the night of the new moon.

This seems to be the most common time when Rumia somehow cannot use her powers, and witness reports flood in.

There aren't many who have exchanged words with her, but it is doubtful you will be able to talk with her.

It's probably dangerous to attempt a conversation(*3).

3: Even though she looks young, she eats humans.