Remilia Scarlet
Remilia Scarlet is the 500 year old owner and head of Scarlet Devil Mansion, the mistress of Sakuya Izayoi and Hong Meiling, and older sister (and guardian) of Flandre Scarlet. She has short blue hair and crimson red eyes, wearing a pink with red accents dress with red heels. She has the classic bat wings that usual vampires have and is photosensitive and weakens against sunlight, so when she travels, she must take a parasol with her. While Remilia appears, and at points, behaves, like a child, she has fearsome magical powers and a reputation to match, being known throughout Gensokyo as the "Scarlet Devil." She has the ability to manipulate fate, which she uses rarely, and carries the weapon known as Gungnir, a spear that always hits its mark, which is made of demonic energy. It holds a strong magic, but at a lesser level than Laevateinn, Flandre's weapon. A little known fact is that Remilia has a very light appetite, thus when drinking blood, her victims almost never die from their wounds.
Flandre Scarlet
Flandre Scarlet is the 495 year old younger sister to Remilia Scarlet and the "dirty little secret" of the Scarlet Devil Mansion. Because of her unstable personality and massive destructive power, she lives in the basement of the Scarlet Devil Mansion. She's immune to holy objects, items and prayers and has incredible physical strength, so her sister ordered her not to leave the mansion for nearly 500 years. She knows very little about the outside world and suffers from multiple personality disorder, usually talking to herself from different "view points." Flandre had short blonde hair with a longer lock tied in a side tail and scarlet eyes, wearing a red and white dress with red shoes and very odd wings. Her wings have multicolored crystals dangling from them, which are rumored to be artificial wings but hasn't been proven. She holds the power to destroy anything and everything by crushing the "eye" which means she locates the area of an object or being where tension is the highest and pours her power into it, effectively crushing it without even needing to touch it. Flandre demonstrated this power when a giant meteorite threatened to crush Gensokyo. As she says, "I just squeezed a little and the meteor went BOOM!" She's never gone outside the mansion walls and has never met humans, and her power is so enormous that she's unable to go easy on enemies, which is one of the main reasons why she's locked inside. She carries the weapon Laevatinn that's magical power is even greater than the Gungnir.
Sakuya Izayoi
Sakuya Izayoi is the Chief Maid at the Scarlet Devil Mansion. She works for her mistress, Remilia Scarlet, and is apparently the only human working at or living within the mansion. She has the power to manipulate time, and with that, space, but unlike the Sakuya is Earthland, she has complete control over this element. She is known to place knives in midair and resume time to allow these knives to fly towards her targets. Stopping time is also handy way of doing large amounts of maid work in a short time. Sakuya has short silvery white-blue hair with two locks worn in braids with green bows and dark blue-gray eyes. She wears a blue-black and white maid's outfit with a green sash around her waist and a bow tie with black stockings and black heels.
Hong Meiling
Hong Meiling is the Scarlet Devil Mansion's gatekeeper, though she's known to be a slacker and usually takes naps instead. She's a youkai with long red-brown hair and green eyes, wearing a green Chinese military uniform. She is a master of Chinese martial arts and uses them often in battle. Meiling, as she goes by her last name, is a very friendly youkai, in fact even excessively friendly as she'll chat with anyone who passes by while on the job, unless they try to trespass. Despite being somewhat a jokester and being uncontrollably friendly to anyone, she is regarded as being a very difficult gatekeeper to pass.
Patchouli Knowledge
Patchouli Knowledge is the very sickly friend of Remilia Scarlet and is a magician, librarian, scholar, and teacher, serving as an unofficial mentor to other magicians, but mainly Marisa Kirisame, who usually comes to steal her books. She spends most of her time in the mansion's library reading and writing magic books. It seems that she's capable of very powerful magic of all kinds, using many elements in a single spell, but due to asthma and general poor health she's often unable to recite her spells. Patchouli has long purple hair and purple eyes, wearing a purple dress with a miniature cape.
Koakuma
Koakuma is a devil that is suspected of originating from Makai, but very little is known about her. Even her name, thus everyone in Gensokyo calls her "Koakuma" which means "Little Devil." She appears to be Patchouli's assistant, or familiar, or even both. She's very obedient, however, and listens carefully to Patchouli. Koakuma is even usually assumed to be a "fangirl" of Patchouli and expresses this when Patchouli uses a spell by standing with amazed eyes and squealing. She knows the names of all Patchouli's spells and what they do, as well. She wears a black dress with a white collar and sleeves, and a red tie, and has long red hair and red eyes, with black bat wings attached to her back and head.