The final boss. She's been the mistress for about 500 years.
She doesn't clarify this herself during the game, but she is a vampire. She blanketed Gensokyo with a magic mist in order to prevent sunlight from reaching her. Although she has been alive for 500 years, her personality is that of a selfish child.
She is respected by most youkai, but her charisma doesn't stem from her personality; rather, it comes from the fear that they have for her kind. She has one younger sister, Flandre; nothing else is known about her family.
She is a light eater. In other words, she can drink only a little blood at a time and must leave the rest behind, so the humans off of whom she feeds become a bit anemic, but usually stay alive. Due to that fact, she is never able to increase the number of her kind.
She often spills more blood than she consumes. The spilt blood dyes her dress a deep scarlet, which is what gives rise to her title, the "Scarlet Devil" (紅い悪魔, Akai akuma).
She swears that she is a descendant of Tepes, but nobody is certain whether she is truly related to the Vlad "Dracula" Tepes.
Well, let it be known that she is not.
Master of the Scarlet Devil Mansion. She looks young, but she's actually a vampire who's over 500 years old.
Weak against sunlight, she has to take a parasol if she wants to go out in the daytime.
Her personality is somewhat childish, and she's got maids who are basically at her beck and call,
so she can be as egotistical as she wants. She's immensely powerful, so she can really kick up a fuss.
Faster than the eye can follow, strong enough to crush boulders, powerful enough to
manipulate demons, she's so strong it's almost not fair, so she doesn't care much for subtle technique.
She may be weak against sunlight, but she has a pretty strong constitution, so as long as some bit of her
still remains, say, a little bat, she can regenerate any time. She's dreadful to have as an enemy, but
she's not exactly the sort of person you'd want as a friend, either.
A vampire who resides in the Scarlet Devil Mansion.
She can manipulate fate. She has apparently lived for over 500 years.
Considering how long she has lived, she acts rather childishly.
Creatures of her kind forfeit their growth and maturity in exchange for eternal life.
In other words, she can live forever because she never grows up.
It goes without saying that she is weak against sunlight, can't cross flowing water, hates garlic, and despises sardine heads. Crosses have no effect on her.
It puzzles her to hear that her kind are supposed to be weak against such a thing.
She uses bats and arrows as her weapons. She can spawn an unlimited number of bats from herself.
In the middle of a lake in Gensokyo, there is a scarlet mansion.
She is the mistress of that mansion.
She is very childish even though she has been alive for more than 500 years.
Devils, including vampires, are hated with a passion by both humans and youkai, because their kind tend to be self-centered and selfish.
Remilia indeed is no exception. Type-B blood tastes the most delicious to her.