There are two vampires in the Scarlet Devil Mansion.

The older sister and the mansion's mistress, Remilia Scarlet, and her younger sister, Flandre Scarlet.

Flandre seldom leaves the Scarlet Devil Mansion (*1), but her existence has been confirmed by humans that enter it on occasion.

She has unusual seven-colored wings, and her hair is a light blond color, but her build and apparent age are similar to that of her older sister, Remilia.

The two wings on her back are of an irregular shape unlike those of any living creature, youkai or ghost.

She has few friends even among the youkai of the Scarlet Devil Mansion, and spends most of her time in isolation.

Even her older sister Remilia is seldom seen together with her.

As a result, much about her is shrouded in mystery.

It is said she possesses the ability to destroy anything at all even without touching them.

Everything that is made for her to play with ends up broken, so she probably doesn't have many playmates.

Her method of destroying things so effortlessly involves pouring her power into the "eyes" of any material where its tension is the highest.

She can use her ability to cause these "eyes" to move into the palm of her hand.

In other words, by crushing the "eye" held within her hand (*2), she causes things to break.

It's a truly frightening ability with no real weaknesses.

1: Perhaps she's locked away, but it's also rumored she's a shut-in.

2: When she clenches her fist, the subject breaks.

"Sometimes when I sneak into the Scarlet Devil Mansion like I own it, I run into the little sister. I had to slip by without drawin' her attention, but after goin' through all that to get into the place, I was hopin' I wouldn't run into her." (Marisa Kirisame)

What a terribly selfish report.

"I doubt she can fly with those wings." (Reimu Hakurei)

It is plausible she cannot (*3).

"I saw her shadow wandering around the mansion while I was at an outdoor party at the Scarlet Devil Mansion. It was truly frightening. I knew it was her just from the silhouette, but she doesn't get to join many parties." (Anonymous)

Almost like something from a horror story.

3: Don't worry, everyone is able to fly even without wings.

Since it's unlikely anyone will ever see or meet her, there isn't anything of which to be aware, but all you need to remember is that there are two vampires that live in the Scarlet Devil Mansion.

Even if her older sister Remilia is away, you should remember that there's another vampire inside the mansion, and not sneak in unprepared.

There are many mysteries to her abilities, and such simple things as the range of her ability and how to defeat her are unknown.

The one thing that can be said is that it is an extremely dangerous ability.

On top of that, she also possesses the usual superhuman strength attributed to vampires, so it would surely be impossible to put up a fight against her.