Hijiri Kasuga

Appearance
She bares a striking resemblance to Arin Kannazuki, though with more expression and presently longer hair.

Personality
In her first appearance, she has a tsundere-type personality. Obviously smitten with Arata, she nevertheless reacts violently (not without some justification, granted) to his perverted antics. She also becomes slightly distressed when Arata seems attracted to Azami Lilith.

However, the above scenes were not the real Hijiri but Sora acting based on her personality. When the real one appears again, she is much calmer about Aratas antics, jokingly stating that Arata constantly did things like that. She exhibits Yandere tendencies, as she nearly kills Arata while claiming she'd just resurrect him later after she'd killed the Trinity Seven. She also shows small periods of extreme vulnerability to Arata, nearly collapsing in tears when he promises to take her back from the Evil Mage side.

Her true motivation is to destroy the system maintaining the world that uses the Magic King as a method of death and rebirth. She claims that she cannot forgive the world for taking away his ordinary days, proving beyond doubt that she values Arata more highly than the world, or anything in it.

History
After Hijiri was engulfed by the "Breakdown Phenomenon" Arata created, she was expelled from the world to the "outside." It was truly a "world of nothingness," she learned how she'd been living in such a wonderful slumber, like everything until that point was a dream. But, somewhere inside, she was satisfied.

Then, as her sense of time was leaving her, and her consciousness was fading away. She was suddenly able to see into the "world" from the outside. There she saw a future, where Arata and the Trinity Seven had destroyed the entire world. The world, had been reduced to nothing by the birth of the Magic King and the Trinity Seven. And then a new world was reborn. However, the Magic King and Trinity Seven would meet again, and once again the world crumbled. She watched the world be destroyed by the Magic King and the Trinity Seven over and over again. That was the future awaiting the world, a never-ending cycle with no way out. She knew the same would happen there eventually. A Magic King Candidate would become the Magic King, and together they would destroy the world. That was why she couldn't forgive the world. For treating Arata as nothing but a tool for its reincarnation.

She didn't want Arata to become the Magic King of "Imperium," so she and Ish Kerioth would destroy the world instead, and make a world Arata could enjoy freely.

Abilities
She has mastered Ruina, Baltan, and Analysis of the Ira Archive. By mastering three separate thema, she already has what it takes to be a "Trinity." She seems to cast spells using the magic system Chaotic Rune, which is based on Norse Runes.

Hijiri received the Magic King Element from the "Ruined World," after being disintegrated by Arata.

By making use of the Magic King Element, she is able to take on the form of an archive. The manifested form of the archive Ira, "Satan." To do this, Hijiri was required to master three separate Thema from the Ira Archive.

Hijiri is powerful enough to simultaneously have contracts with more than one of the legendary grimoires. She received a magic king element from the "Ruin World," after being disintegrated by Arata. a high-level transformation that goes even beyond magus mode.

Hirji can't stay in the world for extended periods. Her body and everything of her's had been broken down, and she was nothing but an existence swaying between space and time.

Baldr's Blessing
Baldr's Blessing, is a Vegtam spell that encompasses both offense and defense. Bald is also a legend among gods.

Arin Kannazuki
Arin and Hijiri have an unknown connection, as they both not only are physically identical, they use Chaotic Rune to work magic.

Trivia

 * Hijiri's manisfested form of Ira is a reference to the demon Satan. In Christian mythology, Satan is often considered the demon most associated with the sin of wrath.