Erda of Cassiopeia

Erda has the appearance of a young teenager. She is an attractive young woman with an athletic body and a slim build thanks to her training as a Saint. Her black hair is somewhat long enough to reach slightly above her shoulders and is styled with bangs on the right side. When Erda isn't wearing her Cloth, she wears an outfit that showcases her tough personality. In this case, she's dressed in a biker jacket and a black blouse that only covers her upper torso and exposes her navel. She wears dark-colored jeans held up by a belt that's a darker shade than her pants and has a diamond-shaped buckle adorning it. She also wears cowboy boots. A characteristic feature of Erda's attire is the scarf she uses to cover her neck.

Erda has a personality opposite to what her status as a Saintia suggests, given that the Saintias are ladies-in-waiting of Athena and have quite refined manners. In this case, Erda shows a rather rude personality, like that of a rebellious and independent young woman, who shows no fear. Erda does not hesitate to challenge her enemy, if she believes she is doing the right thing, even if this one is a powerful Gold Saint like Deathmask. Even when her personality is somewhat impulsive, she is a person who is willing to forgive and listen to the reasons of others, to judge their actions, as shown when she saw that Deathmask had destroyed the Saint Academy in order to finish off the Dryads that make up Eris's army, asking him if it was for that reason that he had to destroy the Saint Academy and take the lives of the apprentices, but upon hearing Deathmask's selfish reasons, she again reacts with anger and helplessness for what happened. Erda returns on her motorcycle to the Saint Academy, but upon arrival, she finds the Saint Academy completely destroyed, in the remains under a column she manages to see her friend Mito, who is still alive, with her last breath she tells her that they had been attacked by surprise and then asks her to flee, after these words Mito dies in Erda's arms. After what happened, Deathmask, who destroyed the Saint Academy, appears before her, seeing that he was a Gold Saint, Erda cannot believe that he was responsible for such a massacre, but Deathmask tells her that since they are traitors to the Sanctuary, he does not have to justify his actions.

Upon hearing this, Erda, determined to avenge the deceased young women, puts on her Cloth and then uses her Greatest Eruption against the Gold Saint, but only manages to burn three of Deathmask's hairs. Deathmask recognizes that it was a good technique for a Bronze Saint but that she is no match for a Gold Saint, and at that moment he attacks her with a finger, destroying part of her Cloth. However, Erda does not give up and sets her cosmos on fire to the maximum, impressing Deathmask, who decides to use his Sekishiki Meikai Ha technique to send himself and Erda towards the Yomotsu. In the Yomotsu, a spirit that takes the appearance of Mito approaches Erda, promising to give her the necessary power to defeat her rival. Erda knows that she is not the real Mito, but she is unable to stop her since the power of discord begins to corrupt her, darkening her Cloth, but at that moment Deathmask appears and eliminates that spirit. Deathmask explains that these spirits are the surviving subordinates of the goddess Eris and that they are her true prey. Having lost their bodies after Eris's defeat, they were trying to possess all the bodies of the young women who were at Saint Academy. Deathmask uses his Seki Shiki Meikai Ha to destroy all the spirits that were in the Yomotsu, and warns Erda not to try to continue fighting him or he will do the same to her. Erda then understands that Deathmask sacrificed the academy to prevent them from falling into the clutches of Eris's army, but she does not understand why he did it without feeling the slightest remorse. Deathmask laughs at the young woman for being so innocent, and tells her that in reward for burning three of his hairs, he will get rid of the corpses for her, then when Erda returns to her body, she only finds the remains of Saint Academy in flames.

During the invasion of Eris's army to the Sanctuary. Erda meets Juan and Georg, and judges them for what happened previously, indicating that she cannot trust someone who has raised his hand against Athena. Later, when the Temple of Eris has approached the Sanctuary, Erda jumps on her motorcycle towards the Temple in the sky. Inside the Temple, she meets Shōko, who was being attacked by the temple's roots, she tells her to get on her motorcycle, because if she is not faster, the roots will trap her. During the trip, Erda hears Shōko's name and recognizes her as Kyōko's sister. The young women stop when they reach a wall formed by the roots of the Womb (tree). Rigel appears there, he tells Shōko to take her to Kyōko. Erda recognizes and attacks Rigel, while warning Shōko not to trust him. The three Saints begin to talk, Rigel convinces Shōko to accompany him, though Erda is unsure if she can trust him. After Aiolia destroys the Temple's core and Saga absorbs its power, the Temple begins to collapse and the roots begin to attack violently, Erda finds herself fleeing from the roots, but before they can reach her, a wall of ice appears to protect her, she recognizes Katja, who tells her to jump, to which she obeys and jumps leaving behind her motorcycle (which is destroyed by the roots). Katja explains the situation and tells her that they must flee, but Erda tells her that Shōko is still in the Temple. At that moment, the roots destroy the entire area where they are, revealing that Xiaoling was captured by the roots. Before they could be captured, Juan appears and uses his abilities to create a barrier around them and Georg saves Xiaoling.

The Saints begin to talk about what happened, and at that moment they observe Saga, who thanks to the energy of the core, has become a divinity, the Saints escape from the Temple before it finishes collapsing. Erda and Katja travel to Olympus in search of a weapon to defeat Eris, upon arriving at the Temple of the Moon they are attacked by the Satellites, but they manage to pass through the rain of arrows. Inside the Temple they are attacked by an arrow, after this Ryuthos appears, who is confident that he can defeat the Saintias, but before he can attack again, he is held by Erda. Ryuthos begins to scream for help to Callisto, the leader of the Satellites introduces herself and after a short conversation with the Saintias, Callisto offers them her help, but first they must go through a ritual to purify their bodies of the impurities of their hearts, Callisto throws two arrows which stick between Katja and Erda's chests. Erda regains consciousness and realizes she is in the prison outside the Temple. She remembers what happened and tries to remove Callisto's arrow. Ryuthos, who was hiding behind a stone pillar, explains to Erda that she will not be able to remove that arrow and should only stay still for a while, since if Callisto had wanted them to, they would be dead. However, he has decided to give them a chance to purify themselves. These arrows will destroy the impurities in their hearts, so they can try to enter the Temple again. Erda begins to laugh and explains that she will not get rid of her hatred for Deathmask and does anyone believe that she would accept being elegantly disguised as scum? After this, Erda pulls the arrow from her chest, but this causes the Evil Seed that was inside her to flourish, which grants a new body to Deathmask's soul, who appears before Erda.

Ryuthos considers Deathmask an evil being trying to desecrate Artemis's sacred land and attacks him with his bow, but his arrow is returned and Erda throws herself to save him. Erda attacks Deathmask with her Greatest Eruption and asks Ryuthos to take this opportunity to flee, but Deathmask stops the attack with one hand and explains to Erda that she should get rid of Ryuthos, so she can fight without worrying about the weak, Erda asks Ryuthos not to worry. At that moment, Callisto notices Deathmask's presence and tries to seal him, but the power of the seal cannot stop the Gold Saint, who decides to leave the place and says goodbye to Erda and Ryuthos, destroying the entire area. Erda throws herself to protect Ryuthos from the energy blast. During the explosion, Ryuthos is teleported away by Callisto, who also seals the entire area. Ryuthos watches the prison from the Temple and Callisto scolds him, because she had warned him not to approach those humans, so she will forgive him just this once, Ryuthos tells her that he doesn't think they are that bad because Erda tried to protect him even though she was in his way. Ryuthos asks what will happen to them, to which Callisto replies that he doesn't have to worry about that, since the area where Erda and Katja were has been removed from Olympus and the evil beings will not be able to approach the Temple.

Ryuthos goes to find Erda who after the attack of Deathmask ended up trapped somewhere in the valley below Olympus, Ryuthos uses the Boots of Hermes to travel to the place where no one can reach. There, he finds Erda on the bank of a river and after greeting her and explaining that Katja had completed her mission, Ryuthos tells her to fly her to the exit; Erda holds the young man's feet so they both fly away, on the way Erda claims why she has to travel this way and Ryuthos explains that he can't carry her any other way because she is too heavy. Erda reminds him that he didn't want humans to touch him, but Ryuthos replies that he couldn't leave her there because if he didn't return the favor his pride wouldn't let him live, after these words, Erda congratulates him and tells him that she didn't expect lesser words from the man who can carry her and more or less fly.

•Greatest Eruption: Raises his right arm concentrating his cosmos in his right hand, to subsequently call the force of nature, thus creating a volcanic eruption that is thrown at the enemy, the magma or fire is thrown against his rival in the form of a spiral tornado, in this way his opponent is reduced to ashes •Burning Lava Rain: He ignites his cosmos to the maximum, and raises his right arm concentrating his cosmos in his right hand, to subsequently launch a volcanic eruption against the enemy in the form of a shower of tiny meteorites, the magma thrown against his rival in the form of thousands of meteorites, in this way he can reduce his opponent to ashes.