Algol

Algol (アルゴール, Algol) is a Celestial Star Spirit as well as a former [Demon Lord]. In the past Algol was known as one of the "Three Great Problem Children of Little Garden", alongside Shiroyasha and Queen Halloween, but now she is simply a slave to the leader of the Perseus community.

Appearance
Algol's sealed form fits the appearance of one titled a Demon Star. Her body is large, at least three times the height of any of the main characters, and rather skinny. Dark grey skin, large black wings, large red eyes like a snakes, sharp lips and purple, wavy hair in jagged shapes. Algol wears a single one-piece outfit with puffy sleeves and a torn skirt. Leather bindings cover most of her body and wings, the bindings on her legs used to make her skirt look more like pants. On her wrists and ankles are silver shackles with broken chains.

Algol can increase her size, doing so causes the shackles on her ankles to be broken and some of the black bindings to break off her body. Algol's eyes turn more upright and sharper and her mouth becomes wider, making her seem more sinister.

Personality
Nothing could be told of her personality for she did not speak nor did she do anything that showed her own personal thoughts besides following her master's orders obediently. Perhaps it is the rule of Little Garden that makes her obedient but it could also be her scheme. Hence, nothing can be concluded for her present day.

Even so, Algol was described as being one of the original "Three Problem Children of Little Garden" in the past, alongside Queen Halloween and Shiroyasha. Before being defeated, Algol was a rather arrogant and vain being, her verbal tick being “Al-chan is a super beauty!". Shiroyasha remarked that Algol's personality made her cry many times, meaning Algol had a mean streak to her. Algol was stated to being prideful and rather ungrateful, as she showed no gratitude towards Athena for being her overseer and even insulted her.

While there is no proof besides Shiroyasha's words, it was rumored that Algol could get drunk off of holy wine with just a sip.

Relationship
Laius Perseus - The contracted master whom she has to obey. As Algol's powers are in relation to her master, she is currently very much restricted in her powers to the point of the restrictions materializing in the form of her chains. A simple master-servant relationship and nothing more.

Shiroyasha - Algol must have enjoyed tormenting Shiroyasha a lot in the past as Shiroyasha stated that Algol made her cry a lot. Naturally, the two are not on good terms.

Queen Halloween - Not much is known about their connections other than being declared "Problem Children."

Sakamaki Izayoi - Algol fought with Izayoi under her master's command but was easily defeated with her Gift usage shattered in mid-beam.

Background
Algol was said to have roots that spread all the way back to the ancient Mesopotamia. At that time she was hailed as a Mother Earth Goddess, though she gradually changed with the changes of culture and advancement of Astrology. She steadily grew away from being a spirit of Earth. The reason she changed into her form as Celestial Spirit Algol would be her appearance in the Masoretic text of the Old Testament.

Using this, Algol began to spread various demons and poisonous animals (snakes, spiders, and scorpions) throughout various worlds and ages, and declared war against the Buddhist Deities. After many hardships, she was finally sealed, but the deities of the Old Testament, where the roots of her power came from, refused to look over her because of how much of a "pain in the ass" she was. She was passed around from place to place until finally the Greek Mythologies took her in.

But, Algol decided to agitate Athena, her overseer, by showing off her beauty and hooking up skills and finally insulted her beauty. Athena bought the fight and the war. Their fight made many worry that it would develop into a huge war, but Athena’s group gained an advantage in a unusual form.

Algol’s spiritual power had been shrinking because she was taken in by the Greek Cosmology. As a result, while Algol was drunk, she was assassinated/eternally bounded to Perseus.

Volume 1
Algol was summoned down by Laius to do battle with the [No Name]s. Once she was summoned she unleashed a roar that was heard throughout the Game Stage. When ordered Algol activated her power, creating a ray of black light that pierced the Colosseum wall, which then the beam expanded and covered everything in the Game Stage but the Colosseum. Algol followed the orders of Laius and began to attack Izayoi. Algol as instantly overpowered, Izayoi catching the leather binding she used as a whip, destroying the snakes she used to bind him, and being able to match strength with her in a hand lock, even as she changed sizes.

Algol was ordered to use her most powerful Gift, but even as she unleashed it, Izayoi destroyed the petrification beam with a kick. Algol was unable to stop Izayoi punching her in the forehead, breaking through her head and fracturing her skull, causing green blood to pool out. Algol was blown back into the Colosseum seats due to the punch. In the light novels Algol was able to make one last stand and charged at Izayoi alongside Laius. Naturally she was defeated.

Gifts and Abilities
Being a variable star, Algol has had great magical capabilities since ancient times. She used to have the power to create and spread any sort of poisonous animals or demon, but due to her sealed state she can only perform a handful of actions.
 * Petrification: Algol's main gift, the power to turn anything to stone. Her power was capable of turning everything within the Game Stage, minus the Colosseum itself, into stone with her power. It has been stated that using her Gift at full power could petrify an entire world. The power takes on the form of a black and purple beam that comes from her mouth (Eyes in the Light Novel) and can decimate everything in its path before expanding and petrifying the area.
 * Shapeshifting: Algol is normally sealed within the necklace around Laius' neck, but when summoned she can take on her sealed form. Whenever she must she can increase both her size and body mass.

Etymology and Mythology
Algol is the name of a star system (composed of Beta Persei Aa1, Aa2, and Ab) in the constellation of Perseus. The Algol "star" is variable star/binary star.

The name Algol is from the Arabic raʾs al-ghūl (رأس الغول, litt. head (ra's) of the ghoul), it's also well know as Demon Star. In the Perseus Constellation Algol's star is the eye of the Medusa head Perseus holds.

Trivia

 * Ironically it is said the best time to see the Demon Star is during Halloween.
 * Algol is also known as "Medusa" and "Lilith".
 * The word Alcohol comes from the name Algol. This comes from the saying that “alcohol is the demon drink that leads men to depravity”.
 * This thing is a bit made up by Author-sama, the term is from the Arabic is كحل (al-kuḥl, "kohl, a powder used as an eyeliner"). So it's not really from Algol, but it somewhat changed after to be like the saying say: the demon drink.
 * The reason why the Celestial Spirit of the fluctuating star Argol changed her name into Algol is rumored to be because of the influence of the drunks that worship her.
 * The true nature of Algol is a pair of binary stars.