Flandre Scarlet is a vampire and a magical girl. She lives in the basement of the Scarlet Devil Mansion and is also Remilia's younger sister. Flandre met Reimu and Marisa for the first time when they came to resolve the Scarlet Mist Incident. Before that, she had never set foot outside.

"Kagome, kagome... Who's standing behind you? A barrage of bullets!" Flandre's Spell Card surrounds its target with bullets and then throws more bullets at them. This is a risky attack that can easily go out of control, but it suits the crazy young vampire quite well, as Marisa once said.

Flandre is said to be slightly insane, but this is difficult to believe when you look at her. Those who encounter the young vampire are easily deceived by her chaotic way of speaking as well as her childish appearance and behavior. Flandre idolizes Remilia, but her unstoppable destructive power actually surpasses that of her sister's.

Although vampires attack people to feast on their blood, they do not kill them. After all, why would one cut off their food supply by killing the source? However, Flandre ends up blasting everything because she is unable to hold back. She might not even be able to tell the difference between the cakes and tea she has every day and a living human...

Her power is so incredible that she breaks anything she grips. It is a mystery how Flandre is able to wreak such havoc, but she is forbidden from leaving the Scarlet Devil Mansion due to the danger she poses to her surroundings. It is not quite clear what her relationship with Remilia is like, but the sisters seem to be getting along fine from an outside point of view.