The members of Astral fail in their efforts to capture a demonic hound due to the incompetence of its president, Itsuki Iba, and the hound is claimed by Adilisia Lenn Mathers, the head of Goetia. Afterwards, Astral is approached by Shōko Kunugi, one of Itsuki's classmates from school, for a mission to find her missing grandfather. However, her grandfather transformed into a demonic creature, and Astral members Honami Takase Ambler, Mikan Katsuragi, and Ren Nekoyashiki go to reinforce Itsuki. Itsuki reveals his Glamsight eye, and under his orders, the Astral members defeat Kunugi's grandfather. At school later, Itsuki is approached by Adilisia and Honami, who bicker in the process. However, when Kunugi says hello to Itsuki, both Honami and Adilisia angrily punch Itsuki in the head.

As the Astral members converse about dates and corresponding unluckiness, Itsuki complains about the responsibilities of becoming president. As he takes a walk from the city, he is confronted by Adilisia, who is incensed that he is unaware of Goetia, and uses her magic to attempt to force him to sign a magical contract to give Goetia the sole rights for a recent bid. Honami stops her, and Adilisia retreats. Later, Nekoyashiki asks Itsuki to join Honami in resolving a spell wave contamination. However, a mansion appears, and Honami recalls how in their youth, Itsuki saved her from a demonic creature, and gained his Glamsight in the process. Honami saves him from a Dullahan in the mansion, fulfilling her desire to protect Itsuki since that incident. At school, Adilisia arrives as a new student, much to Itsuki's embarrassment and Honami's anger.

Itsuki arrives late for an appointment at a shrine due to allowing Mikan to buy souvenirs at a festival. The request is from Shinogi Minagi, who requests a saniwa, or spirit medium to convene with Futsunushinokami, the god of the shrine, in order to revive her comatose brother, Moroha Minagi. Although Adilisia and Honami are against Itsuki taking the job, he agrees after seeing Mikan's enthusiasm for doing it. However, as the ritual is being conducted, Kagezaki, a member of the Association, arrives, and tells Astral member Manami Kuroha of Takeminakatanokami, the other god of the shrine. He tells of the incident where Shinogi and Moroha summoned Takeminakatanokami, but Moroha was forced to invoke Futsunushinokami's power to stop him, leaving him in a coma. Mikan, with emotional support from Itsuki and an arrived Honami, manages to seal Takeminakatanokami, and Moroha awakens. On the train back, Kuroha teases Honami for caring about Itsuki and showing up to save him.

Itsuki is in the hospital with a broken leg, where he converses with Manami Kuroha, a ghost inhabiting the hospital. Kuroha is overjoyed that someone can talk with her, and she asks Itsuki about Astral and its workings. Meanwhile, Honami and Nekoyashiki investigate a source of magical pollution near the hospital. Nekoyashiki comes to Itsuki, and dispels a set of bloody hand prints. Honami arrives and the three determine that a dead mage is the cause of the pollution. Elsewhere, Kuroha is consumed by a mass of flesh, and it attacks Itsuki, Honami and Nekoyashiki. They determine it was the result of a mage attempting to acquire immortality by eating souls. As they prepare to destroy it, Itsuki reveals his Glamsight, and the three succeed in rescuing Kuroha. A few days later, with the members of Astral present, Itsuki invites an overjoyed Kuroha into Astral.

Due to the low amounts of jobs Astral has taken since Itsuki took over, Kagezaki threatens to disband Astral if they do not take on a difficult mission. They are assigned to remove the magical pollution creating a vast sea. Goetia arrives as well, and summons a host of birds to attack Honami and Itsuki. Honami dispatches the birds, and Adilisia arrives. However, the sea engulfs Adilisia and Itsuki and then freezes, trapping them. Below the ice, Adilisia reveals that the pollution is caused by a Goetia member that broke a magical taboo, becoming magic, and swears Itsuki to secrecy. The mage is revealed to be Oswald Lenn Mathers, Adilisia's father. He attacks Adilisia and Itsuki, but Honami's arrival saves them. Oswald withdraws and Itsuki makes Honami promise not to reveal the pollution's source before fainting.

Kagezaki confronts Adilisia over a rumor that a Goetia member broke a taboo, but Itsuki's interjection convinces him to leave. Itsuki forms an alliance with Adilisia to destroy her father. Outside, Honami apologizes to Itsuki for underestimating the magical pollution. Itsuki then asks her why she joined Astral, and she whispers to herself that it was since Itsuki was present. Oswald is traced to an amusement park, where Adilisia acts as bait. Beforehand, Adilisia tells Itsuki that she does not want to destroy her father, but rather protect his honor and dignity. Oswald arrives and despite the combined efforts of the Astral members and Adilisia, they are defeated. However, a voice compels Itsuki to reveal his Glamsight, and directing the Astral members, they defeat Oswald. Itsuki is then admitted to a hospital with a broken leg, and Adilisia lies down beside him. Outside, Honami and Nekoyashiki talk about the Glamsight's properties, and Honami comments that she will always protect Itsuki.

Itsuki meets a girl in a park, and seeing her alone, gives her his food and his business card. She later goes to the Astral residence, asking to obtain a basilisk eye, shocking the Astral members. However, with the offer of a valuable gold coin, they accept. They proceed to the basilisk's lair, where the basilisk manages to trap Lapis and Itsuki in a room, and subsequently overwhelms Mikan's protection charm. Itsuki then reveals his Glamsight, and the Astral members dispatch the basilisk. Itsuki then collapses from the magical pollution, and Nekoyashiki barely manages to purify him. Later, Lapis arrives at Itsuki's bedside, and after arguing with Mikan and Honami, who realize she is a homunculus, destroys most of the room in an explosion. Nekoyashiki then realizes that she is being controlled by Yudaikus Tholoide, one of the founders of Astral.

he Astral members go to a hot spring in order to cure Itsuki's eye, as hot springs are situated on magical ley lines, but note that the magic is too weak. They travel up the mountainside, and Kuroha suggests a competition to find a ley line. Honami and Adilisia claim they are above it, but note that they would both want Itsuki's affection as their prize. When the competition starts, Honami and Adilisia try to find the hot spring, tearing the mountain apart in the process. The group then falls into a hole, where they find a rock that is causing the ley line to break. Combining their abilities, they levitate the rock, enabling the hot spring to regain its power. As the members return to the hot spring, Honami and Adilisia's fight causes the fence between the men's and women's baths to break, embarrassing everyone.

Adilisia raids Tholoide's lab, but is defeated by Tholoide and Lapis. Back in Japan, Kagezaki brings an item once owned by Tsukasa Iba, Itsuki's father, that the Association was holding to Itsuki, but reveals that Tholoide is disputing Itsuki's control of Astral. Itsuki and Honami go to a blimp to converse with Lapis, whom Tholoide speaks through. Tholoide concedes the ownership of Astral to Itsuki, but the two agree to battle to determine ownership of the item. After Tholoide claims that Adilisia is dead, Honami attacks Lapis, and Itsuki unveils his Glamsight. Lapis manages to escape, but Tholoide acknowledges Itsuki's power. Later that evening, the Astral mansion is attacked by Lapis, with Nekoyashiki barely managing to create a barrier against the initial assault. Honami flies from the mansion to meet Tholoide, who reveals he is an automaton. He then knocks Honami to the ground with a punch.

Lapis uses her basilisk eye to steal Itsuki's sight, preventing him from using his Glamsight. However, she retreats after Adilisia arrives, and Adilisia dispels Lapis' spell. Elsewhere, Honami awakens in Tholoide's lab surrounded by a barrier, and Tholoide reveals the item the Association was holding was Tsukasa Iba's grimoire. Itsuki plans an assault on Tholoide's headquarters, and Honami, realizing Itsuki is coming, desperately tries to break the barrier using a spell with her blood, but Adilisia's arrival makes it unnecessary. Itsuki confronts Tholoide, who easily defeats the Astral members with the basilisk eye he took from Lapis. Honami and Adilisia arrive, and Tholoide transforms Lapis into a basilisk to fight them. Itsuki manages to resist the eye's effect, revealing his Glamsight. He frees Lapis, telling Tholoide that as president, he can only aspire to be the best he can. Later at the Astral mansion, they receive a letter from Lapis and Tholoide, who reveals that Itsuki can learn more about his Glamsight in his father's grimoire.

Astral is approached by Diana, the president of the magic items provision corporation Trismegistus, to find a special flower that is seeded within a human body and blooms after their death. As the mission was originally taken by Itsuki's father, Itsuki accepts. However, they are attacked by Li Cheng Chen, a magician that can raise the dead. He tries to take the flower, but Honami takes it, escaping with Itsuki, leaving Kuroha behind. Itsuki resolves to save Kuroha and retain the flower for Diana. Elsewhere, Diana approaches Chen, regretful that she sold him the root for the flower, as he killed a village to seed it with power. Itsuki arrives, and Kuroha manifests her poltergeist powers to free herself from Chen's imprisonment. Itsuki reveals his Glamsight and he, Honami, and Kuroha defeat Chen. At the Astral mansion, Diana thanks Itsuki and while looking at his eye, comes close to his face. A scandalized Honami and Kuroha punch Itsuki after Diana leaves.

With all the Astral members busy, Itsuki goes into the city. Diana later comes to the Astral mansion, and tells Honami and Kuroha that Itsuki asked what girls liked for presents. Immediately intrigued, Honami runs into the city to find Itsuki. Meanwhile, Daphne, Adilisia's maid, reveals that Itsuki asked her the same question, and Adilisia runs to find Itsuki. She finds Honami and the two trail Itsuki into the city, where they find that Itsuki was getting a present for the ghost of a girl. Kuroha joins them and they go to a church, where they found the ghosts of a group of children that died in a fire. As a present, Itsuki, Honami, Adilisia, and Kuroha sing to them, and the church disappears with the ghosts. When they return to the mansion, the Astral members reveal that they've been planning a Christmas party for Itsuki. As they enjoy the party, Adilisia asks for Itsuki to stay with her the next day, and Honami angrily demands to be taken along.

In a flashback, Honami recalls how she attended a wizarding school in Britain, and was widely considered a failure. Despite the criticism, she was fully committed to learning Celtic magic. Adilisia, also at the school, quickly gained the reputation of the brightest and strongest magician in the school. As their qualifying exam for the school, students were expected to survive in pairs in a site of magical pollution. Adilisia was paired with Honami, who refused to follow Adilisia's plan to destroy the source of the pollution and display her superiority. The two separate, but Honami saves Adilisia when she fails to destroy the source of the pollution, endangering the students present. With aid from Adilisia, Honami shows her skill with Celtic magic, and destroys the source. In the present, Adilisia is commenting on their schooling with Itsuki and Kuroha while reviewing old photos. Honami arrives and takes the two home, and when Itsuki asks her why she tried so hard at school, Honami thinks to herself it was because of Itsuki.

Astral is contacted by Kei Isurugi, a member of the school of Onmyōdō that Nekoyashiki once attended, to perform a ceremony at a mountain. Itsuki accompanies Nekoyashiki and Mikan, but they are attacked by Kei during the ceremony. Kei remarks that he lost his sister, Sakuya Isurugi during a similar ceremony three years prior because Nekoyashiki left the school at the time to take Mikan to Astral. Nekoyashiki challenges Kei to a personal duel, and Itsuki upholds this, stopping the arriving Honami and Adilisia from interfering. Despite Kei's use of kuda-gitsune, Nekoyashiki manages to defeat him, with Kei pleased that he was able to pose some level of challenge for Nekoyashiki, his idol at the school. As Kei lies in defeat, Nekoyashiki reminisces on his last experience with Sakuya as the group watches an aurora in the sky.

Shinogi and Moroha Minagi request that the Astral members return a funadama they found to a shrine on a beach. When Itsuki and Kuroha attempt to return it, they are sucked into the past due to the magical pollution in the area. They meet a fisherman, Hyōdō, who explains that he has been attempting to find a mermaid due to the miraculous healing abilities their flesh gives when it is consumed. In the present, Honami, Adilisia, Mikan, and Nekoyashiki are told the legend of the mermaids from an old woman, who recounts that mermaids return to eat those that consumed them. Itsuki and Kuroha are subsequently attacked, and Kuroha manages to call upon the spirit of Hyōdō's wife, which materializes in a funadama, causing the mermaids to chase after it instead, and Itsuki and Kuroha return to their own time. Later, Shinogi recounts that the shrine is being worshipped again, and Itsuki realizes it is likely one of Hyōdō's descendants.

While training in the mountains, Itsuki is attacked by a larva, a magical creature that makes nightmares reality, and is saved by Sekiren, a traveling member of Astral. On Itsuki's request, Sekiren trains him in martial arts. In a break in training, Sekiren visits Astral and asks Nekoyashiki to allow him to take on a mission offered to Astral. Kuroha takes tea to Itsuki, who claims that he is training so that others can rely on him. Magical pollution appears on the mountain, and Kuroha leaves to seek help, but after she and Honami return, Sekiren stops them. Meanwhile, Itsuki is attacked by the larva in the form of an armored soldier, and using Sekiren's training, is able to defeat it without using his Glamsight. Afterwards, Sekiren reveals he set up the conflict for Itsuki's benefit, and advises him to fight with his Glamsight rather than have it control him.

A Goetia ceremony to summon the demon Asmodai fails due to the interference of a former member, Clive Roland, once a disciple of Adelicia's father. Adelicia goes missing as a result and Daphne visits Itsuki during one of his training sessions with Sekiren to find out where Adelicia is. That evening, Itsuki is attacked by Clive, who uses Adelicia's demons, but retreats after Adelicia arrives. Adelicia reveals that she returned to England to summon Asmodai, one of the four great demons that control the other demons of the Ars Goetia, but was interrupted by Clive, who intends to summon Asmodai. Itsuki and Adelicia arrive too late to stop Clive from summoning Asmodai, but Asmodai kills Clive and begins attacking Itsuki and Adelicia. Ituski is able to use Sekiren's Xingyiquan to defend against Asmodai while Adelicia sacrifices her "future" to gain control over the demon. Afterwards, Adelicia tells Itsuki that sacrificing her "future" meant devoting the rest of her life to magic.

Daphne begins searching for Clive in order to find Adelicia, meeting Gara, Goetia's secretary, in the city. Gara is not aware of Clive's location, but after he leaves, Sekiren appears, and Daphne attacks him. Sekiren explains he wishes to help Daphne with her search, and after witnessing Daphne's abilities, questions why she lowered herself to being Adelicia's servant. Daphne replies that she is content to be Adelicia's servant, although she is embarrassed when Sekiren declares his love for her. The two eventually find Clive dead, and confront Gara over killing him. Gara uses forbidden techniques to fuse with a demon, causing Sekiren to realize that he is part of Ophion, an organization of mages that do not follow magical taboos. Sekiren defeats Gara and forces him to retreat. Afterwards, he tells Daphne of his association with Oswald Mathers, notes Daphne is Adelicia's sister, giving up her former blond hair and green eyes to do so, and falls asleep in the grass while proclaiming his love to her again.

Mikan and Nekoyashiki return to Mikan's family, and their extended absence causes Itsuki to inquire as to their status. Suzuka Katsuragi, the head of the family and Mikan's grandmother, refuses to return Mikan to Astral, and reveals that Nekoyashiki has been missing. Itsuki and Honami travel to the Katsuragi estate, where Suzuka offers to consider returning Mikan if Astral eliminates an oni on the mountain. Along with their guide, Tatsumi Shitō, they travel up the mountain to an area where dozens of oni attack them. The three are ultimately engulfed by the magical pollution present, and Itsuki awakens to find Nekoyashiki with Mikan's missing sister, Kaori Katsuragi. Nekoyashiki and Kaori explain that the ritual the Katsuragi are performing places the oni of the mountain into the next family heir, killing them, and Suzuka wishes this to be done to Mikan. Nekoyashiki claims he kidnapped Kaori to prevent the ritual from occurring, but due to a trace placed on Itsuki revealing Kaori's location, Suzuka begins the ritual.

The oni traps Kaori and is subsequently trapped in the Katsuragi ceremony; however, Kaori receives severe pain when the Katsuragi clan members remove one of the oni's horns. Suzuka calls Mikan to be a sacrifice, but the oni breaks free of the ritual. Itsuki, Honami, Nekoyashiki, and Tatsumi arrive and offer to combat the oni, which Suzuka agrees to, although she dismisses any possibility of victory. Using his Glamsight, Itsuki directs Honami in sealing the oni's movement while Mikan and Kaori complete the Katsuragi ceremony. The oni's remaining horn enables him to halt the ritual, but Adelicia arrives, removing the remaining horn with one of her summoned demons. Mikan and Kaori complete the ritual and cause the oni to vanish. Impressed with their feat, Suzuka allows Mikan to return to Astral and requests that Itsuki take good care of her.

Adelicia is forced by the Association to either appoint a new head of Goetia or get married to legitimize her claim. To resolve this, she offers a marriage proposal to Honami. She explains to a bewildered Itsuki that they will only be married as mages, which does not have the same weight as an actual marriage. With aid from Diana, Adelicia and Honami pick out the clothing and jewelry for their wedding while a disgruntled Itsuki accompanies them. At the marriage ceremony, Daphne administers the rites, but before the final stages are concluded, Itsuki takes both Adelicia and Honami and leaves the church. He explains to both of them that he realized that both did not have their hearts in the ceremony, and were doing it against their wishes. Adelicia subsequently contacts the Association to inform them that the marriage is canceled, and she and Honami throw their rings into the river, which Itsuki is later forced to retrieve.

Sekiren becomes concerned after the Sekiren is disturbed by the errosion of a Buddhist idol that crumbles under his touch. Itsuki and Adelicia are enjoying a date. Itsuki and Adelicia are discussing Honami's diligence in resurrecting the lost arts of Celtic Magic and are about to have an intimate moment but are interrupted by Fin Crue who has managed to save Nekoyashiki's cat Genbu but in the process got himself stuck up a tree. On returning to Astral's headquarters, Nekoyashiki rewards Fin with a generous helping of Cream Puffs. Honami returns with Mikan, who is home early from school, and it is revealed that Fin is in fact aware of Itsuki's status as Astral's President, was instrumental in Honami's resurrection of Celtic Magic and claims to be on assignment from the Association to investigation regarding a the breaking of Taboo that Itsuki's involved in somehow. Fin ends his investigation but is followed by Itsuki on leaving. After a short discussion between Fin and Itsuki about Glamsight and what it means to be a mage Itsuki's right eye begins to pain him and he becomes disoriented. A mist descends on the city and the non-magical folk appear to be frozen where they stand. Itsuki is attacked by a dragon hatchling but is saved by Sekiren who destroys the drakling mercilessly. Sekiren reveals that Itsuki's eye patch has been negated and that someone has broken the seals on the dragons. Itsuki concludes that Fin is behind these events and leaves Sekiren to confront him. Honami is assisting Fin in summoning the Dragon under the belief that it can heal Itsuki's tainted eye.

Honami travels throughout the city, writing runes in her blood for the dragon summoning ceremony. Nekoyashiki explains to the remaining Astral members that Itsuki's father, Tsukasa Iba, chose for Astral's headquarters to be in the city in order to keep watch over the dragon, and he casts a spell to retrieve Honami and Itsuki. Elsewhere, Adelicia confronts Fin, who overwhelms her with his magic. Itsuki and Sekiren arrive and Fin quickly disables the latter. Fin reveals that he is a changeling and possesses the Glamsight, which knocks Itsuki unconscious. Nekoyakishi's spell reaches Itsuki, Sekiren, and Adelicia, but Fin disrupts it, causing the spell to leave Itsuki behind. Honami and Fin take Itsuki to a tower, where they begin to summon the dragon. Nekoyakishi surmises the dragon is a sacrifice to heal Itsuki's eye, and that Honami feels guilt over exposing Itsuki's Glamsight to damage from the dragon when they were traveling in a mansion as children.

The members of Astral go to the tower, and are confronted by the dragon. Sekiren, Mikan, and Kuroha begin to battle it, and the others continue into the tower. Nekoyashiki arrives first, but is stopped by Fin's and Honami's combined efforts. Adelicia enters the battle and summons Asmodai, her most powerful demon, and Honami responds with one of her most powerful spells. Nekoyashiki stops the confrontation to prevent the area from being destroyed from the accumulation of energy. Itsuki awakens, revealing his Glamsight and admitting to Honami that he does not blame her for their childhood incident with the dragon. Itsuki and Fin battle, and as Fin conjures an unblockable attack, Honami betrays him, declaring her love for Itsuki. The Association members, headed by Kagezaki, begin to arrive on the scene, and Fin retreats. Due to Fin's betrayal of the Association and a lack of evidence against Astral, the Association acquits Astral of any wrongdoing. Afterwards, Itsuki and Honami go to see the dragon before it is sealed, and upon its request, Itsuki names it "Astral."