Ilias Fragment

The , also known as Ilia or Treis, is a legendary grimoire, the third Chapter of the Ilias Fragments initially formed by the Witch of Witches, as well as the elder sister of Okto. Originally serving Hijiri Kasuga, Ilia has since joined Arata as his grimoire.

Personality
Meek and modest, Ilia normally acts in a polite and reserved manner towards others in most situations. As such, she is usually one of the more serious and level headed characters among most of her peers. Often surprised and exasperated by their eccentric and unpredictable antics, Ilia will generally play the straight man, ordinarily having to rebuke many of their statement and actions. Furthermore, Ilia can be quite pure, mainly becoming easily embarrassed by any perverted matters. Although, surprisingly she can also be especially daring. During Arata's investigation in the Royal Liber Academy's disappearance, she showed him rather immodest visions of her as Hijiri. Nevertheless, Ilia can be very friendly, supporting and watching over those around her.

As a grimoire, Ilia is highly loyal to her master, willing to obey and complete any orders to the extreme. Sadly considering herself a tool, she can become quite cold and ruthless in order to follow her master's will. Under the command of her previous master, Hijiri, Ilia would trap Arata in her dimension barrier, as well as attempt to murder Mira and use Sora as her eternal power source. However, since happily joining Arata, she has mellowed and become more cordial. Ilia cares deeply for her masters, particularly now towards her current master, Arata, whom she has become quite attached to. Notably, she has shown to be jealous whenever he becomes close to other girls.

During battles, Ilia is mostly able to remain reserved and calm, allowing her to collect information, and formulate plans against enemies. As a support grimoire, Ilia relies on her craftiness and intelligence to overcome her opponents. In the fight against Sora, aware that Sora would become vulnerable after using a powerful attack, Ilia was able to defeat Sora by trapping her. Although, when confronted by stronger adversaries such as Astral Trinity, Ilia can become quite afraid and lose her composure. Since joining Arata, she has cheerfully and firmly supported him in even the most dangerous circumstances.

Appearance
Ilias's true form is a small blue ornate book bounded by thin chains that allow her to hang from her master's wrist. Furthermore, she also possesses the ability to change her appearance, assuming various human forms, most notably of her previous master Hijiri.

Human Form: Ilia assumes the form of a young woman with curvaceous proportions and long light green hair held back by a dark cloth like a hairband. Her wear mainly includes a dark long-sleeved mini dress with a cape collar that has white hems and tied together with a red ribbon. Additionally, she also wears black thigh socks and a pair of brown loafers.

History
Ilia would first manifest, along with her sisters including Okto, after the Witch of Witches gathered the Ilias Fragments.

However, Ilia, along with the Astil Manuscript, would eventually form a contract Hijiri upon her birth. As such, their combined support would make Hijiri become stronger than even her parents. After Hijiri was assigned to monitor Arata, Ilia would help assist her against demons that were attracted to Arata. Although, she has mostly taken on the role of impersonating Hijiri while the real one was away. Ilia would also eventually become attracted towards Arata which would reinforce her facade as Hijiri would develop feelings for him as well.

Black Sun
After Hijiri begins hearing rumors of black shadows appearing in her hometown. Ilia would again disguise herself as Hijiri while her master and Sora left high school to investigate. However, after school ended, as she and Arata were returning home, Arata's magic awakened and drained Ilia, reverting her back to her book form. She would eventually be found by Hijiri after sensing the grimoire's distress.

Ilia would remain with Hijiri after she disappeared due to a Breakdown Phenomenon.

Royal Liber Academy
Hijiri would send Ilia to the Royal Liber Academy to lure and detain Arata while she destroyed the world. Surrounding Liber Academy with a dimensional barrier, Ilia would make the Academy appear as destroyed while waiting for Arata.

She was largely successful in this, successfully trapping Arata in her dimension, but also for some reason Mira. When her plans reach the point of killing Sora and Mira, Arata's anger transforms him into Astral Trinity, who proceeds to utterly unravel everything she'd set up and destroy her dimension with a Breakdown Phenomenon.

After Astral Trinity was contained, Arata thanked Ilya for all the times she'd taken care of him and proceeded to ask her to get them out of the dimension, which she cannot do due to the interference of Astral Trinity's Breakdown Phenomenon. After destroying the Breakdown Phenomenon however, Arata's group is transported home, along with her as his second Grimoire.

Abilities
Ilia is a legendary grimoire capable of having her own thoughts and free will, allowing her to act independently or directly provide assistance for her master. As a support type grimoire, Ilia can have a wide variety of magical abilities that makes her a very versatile and reliable ally. Currently, she has shown the following skills: While admittedly not as powerful as Sora in terms of raw power, Ilia's craftiness and composure enables her to conceive strategies and take advantage of weaknesses, allowing her to even defeat Sora. Notably, Ilia specializes in decoding and support.
 * Polymorphism - Similar to Sora, Ilia has the ability to transform or modify her appearance. However, she can only take the form of another by projecting that person's shadow as long as he/she is alive.
 * Magical Barriers  - Ilia can form protective barriers to defend herself against enemy attacks. While these barriers do not fully protect her against all attacks such as Mira's, she can use them to buy her enough time to retreat.
 * Dimensional Barriers - Ilia is also capable of creating large dimensional barriers by isolating an area to another dimension, once enveloping the entire Royal Liber Academy as if the school was destroyed. Within her barrier, Ilia can control and manipulate anything inside the capacity such as teleportation, magic restriction, commanding specters. These barriers often include a linchpin used to hold the barrier together.
 * Illusions - Able to create and project illusions, Ilia once showed Arata an image of her as Hijiri in a naked apron.
 * Sealing - Trapping her enemies by sealing them in a black cube, Ilia is even capable of completely sealing Sora, whom she could use as a source of magic. She was also able to stabilize Lilith's Magic King Element from becoming out of control.
 * Magic Replication - Ilia has been shown to possess the same ability to replicate magic for Arata to wield.
 * Healing - Ilia has been shown to possess healing abilities, reducing magical burdens on Arata's body and alleviating an injured Lilith.
 * Analysis - Ilia is quite adept at analyzing magic, able to quickly understand and identify it's essence.
 * Telepathy - After joining Arata, they are able to communicate with each other telepathically.

Additionally, Ilia is immortal and cannot die due to being a grimoire. After forming a contract, they form a connection which her master can detect her location by focusing on his/her consciousness. Her magic can also be used to replenish and boost enhance her master's magic as well.

Upon Arata forfeiting his Demon Lord Element and magic, Ilia can no longer be utilized by him with the exception of appearing in her human form. Regardless, Ilia still remains loyal to Arata, considering him to be her one true master.

Masters
Arata Kasuga - Prior to Arata becoming a magus, Ilia would secretly take care of him as Hijiri while the real one was away performing missions. After Hijiri's disappearance, Ilia would reunite with him as Hijiri again during his investigation of the Royal Liber Academy's destruction where she would trap him and Mira in her dimensional barrier. Under the orders of Hijiri, she would attempt to convince him to remain with him, enticing him with an image of her as Hijiri in a naked apron before eventually forcibly restraining him. While she would not directly harm Arata, her attempt to kill Mira and imprisonment of Sora would greatly anger him and cause him to transform into Astral Trinity. After being returned to normal, despite her actions, Arata would instead thank Ilia for her care and ask her to join him, which she would happily oblige. Since then, Ilia has become his grimoire, supporting and protecting him through many difficult situations.

Ilia deeply cares and respects Arata, usually treating him in a polite and kind manner. However, she was initially quite possessive of him, but has since mellowed. Although, she continues to become jealous whenever he gets intimate with another girl. Furthermore, while often surprised by his carefree and perverted attitude, Ilia has remained loyal towards him and greatly trusts his decisions. Likewise, in spite of her earlier actions, Arata also cares for her and treats her as a friend rather than a tool which she is especially grateful for. During battles, the two are able to work together as an effective team, using her wide variety of support abilities to help protect him against enemies.

Hijiri Kasuga - Ilia's previous master, Hijiri prior to her disappearance would have Ilia pose as her to take care of Arata while she was away during missions. Ilia would remain with Hijiri after she vanished due to a Breakdown Phenomenon until HIjiri commanded her to lure and trap Arata until she destroyed the world. Although Ilia would eventually join Arata, she is very faithful and cares very deeply for her previous master. After reuniting with Arata, she was willing to kill Mira and other girls close to Arata because Hijiri would be jealous. Likewise, Hijiri did not seem to mind Ilia siding with Arata and would not hold a grudge.

Friends
Sora - As former grimoires of Hijiri, Ilia and Sora have known and worked together for an unknown amount of time. The two become separated for some time after Hijiri entrusted Sora to Arata while Ilia remained with Hijiri after her disappearance due to a Breakdown Phenomenon. Eventually, they would reunite again as enemies after Ilia, posing as Hijiri, trapped Sora along with Arata and Mira in her dimension barrier during their investigation into Liber Academy's apparent destruction. Quickly recognized by Sora, Ilia would soon confront her in battle, acting casual and respectful towards one another despite being adversaries. Already familiar with the other's abilities, Ilia, however, would outmaneuver Sora and capture her in the end, intending to use her as a magic source.

Despite Ilia's actions, Sora does not seem to resent Ilia, having any objections to her joining Arata. Since then, the two have remained amicable towards each other, readily teaming together once more to support Arata. While her mischievous and risque behavior often perplexes Ilia, Sora has once stated that this was because they were close enough to never stop fighting. Arata even remarked that the two were actually quite close even though Ilia denies this.

Family
Okto - As the third Chapter of the Ilias Fragments, Ilia is the elder sister of Okto, whom she has a cordial kinship with. The two would happily reunite within Dante's Gate in spite of Okto's trail to evaluate Ilia's master's strength. However, the grimoires' reunion would become despondant upon learning of their "mother's" death and the capture of their remaining sisters. Nevertheless, the two would agree to cooperate in order to rescue their remaining family members.

Mina Salem- She is the Witch of Witches and wrote the 9 chapters of the Ilias Fragment. Because she created Ilia and Okto along with 7 other grimoires of the other 7 chapters, she is technically their "mother." Ilia is highly devoted to Mina because Mina created them, but she was shocked after finding out Radix Astil killed the mother she had loved so much.

Trivia

 * Ilia, along with Sora, is one of the only grimoires capable of having free will and thought.