|Alias||Darkness of Maddening Death|
|Magic(s)||Lord of Nightmares|
|Manga||Chapter 64The Seven Magicians|
Rubine is one of the twelve demon commanders of Malebranche that resides within Dante's Gate, considered to be the strongest of the organization. After Arata enters Dante's Gate, she decides to directly challenge the former Demon Lord Candidate in order to make him her property.
Despite her impassive demeanor, Rubine can become quite passionate while provoked, particularly towards situations involving battle. Often behaving in a simple and polite manner towards others, she is nontheless willing to use brutal force in order to achieve her desires, being quite confidant in her strength.
Rubine is a young slim woman with a large busom and black hair styled in a bob cut. Her normal attire consists of a dark long gothic dress with an open back and a stomach corset. Additionally, she also wears a dark mourning veil and mini top hat over her head, as well as a pair of dark gloves and an unbrella as an accessory.
Some time ago, Rubine was a normal mage researching the truth of magic before entering Dante's Gate and transforming into a demon before eventually joining Malebranche under the true Demon Lord.
Inside a castle within Dante's Gate, Rubine, along with Arbariccia, encounters Radix Astil while contemplating about Arata. Upon the demon commander's question of her interest in the former Demon Lord Candidate, Radix denies her claim but Rubine quickly detects her lie, becoming provoked and overwhems the grimoire with the intensity of her magic. However, Arbarricia swiftly calms her down before continuing their discussion about Arata which prompts the former to scout him with her magic. Although Arbarricia is unimpressed with his appearance, Rubine comments that he was her type and decides to be the first to confront him. Radix is initially concerned since Rubine is considered as the strongest of the Malebranche, but nevertheless relents in order to continue evaluating Arata as a suitable vessel for her master.
After Arata unexpectedly enters the Eigth Circle along with Selina, Rubine cares for the unconscious former Demon Lord Candidate in the ruins of a church until he awakens. After explaining his situation as well as her identity, the Demon Commander requests that he become her property, although the tempted Arata eventually declines. However, Rubine then decides to use force to change his decision, stating that she is the strongest of Malebranche. After allowing Arata and Selina to prepare, Rubine begins the battle by summoning a reaper servant to attack them, but the Magic Knight manages to deflect the initial strike. Nevertheless, two additional reapers appear to continue the onslaught which Arata once again is able to protect both himself and Selina. When Rubine questions if he will continue the skirmish, Arata confirms in order to rescue Ilia's sisters which the demon commander responds by summoning an army of reapers before preparing to resume the fight.
Considered as the strongest of Malebranche, Rubine posseses magic capable of intimidating Radix Astil and even rival the Demon Lord. In comparison to Arata, Judecca determined that her strength was overwhelming that his chances of victory was less than one percent.
Rubine's Thema is Auxilium, the power of Darkness. As result of her research, when she relinquished her humanity and become a demon, she became embodiment of the concept of Darkness itself. As result, she is almost impossible to destroy, because she will return as long as there is still darkness. She can also draw power from darkness.
She is the person Arbariccia don't want to confront, because even though Arbariccia's can switch when her host's body is killed, Rubine's magic deals physical and spiritual damage which is able to destroy Arbariccia's true form of Holy Spirit.
- Road of Nightmare - A lost ancient spell, Rubine summons a spirit resembling a grim reaper which she controls using threads connected to her fingers. The reaper is proficient in wielding a large scythe with a considerable amount of strength. Furthermore, the demon commander is able to call additional reapers and manipulate them simultaneously as an army to assault her opponents.
Arata Kasuga - As a member of Malebranche, Rubine can be considered an adversary towards Arata and his supporters, however their associations has not prevented them from being cordial towards one another. Notably, Rubine considers his appearance as her type, thus becoming determined to meet early after his arrival into Dante's Gate. The two would initially encounter each other after Arbarricia teleported his party into different Circles where she would care for the former Demon Lord Candidate while he was unconscious. Afterwards, the demon commander would introduce herself to him before requesting that Arata become her property. Despite being enticed by her offer, Arata would ultimately decline which prompts Rubine to challenge him in combat in order to force his acceptance, although she allowed him to prepare beforehand.