Cardinal (Underworld)

Cardinal (カーディナル) is the embodiment of the Cardinal System in Underworld that has inherited the Cardinal System's sub-process of performing error checks on the main process, namely Quinella. At the moment, she resides in the Great Library Room that is linked with the Central Cathedral, but not spatially part of it.

Appearance
Cardinal appears as a scrawny 10 year old girl with brown eyes and curly hair of the same color.

History
Quinella, in an attempt to usurp the seat of god, took the Cardinal System of Underworld into herself, so that she could have no equal. However, doing so, she took in the Cardinal's 2 main processes: the main process, in charge of regulating the world, and the sub-process, in charge of performing error checks on the main process. Although the main process was in control for most of the time, during times of emotional distress, the sub process was able to float to the surface of the thought process and deemed the main process as an error in herself due to directly harming other people with her Fluctlight experiments. After the sub process unsuccessfully attempted to kill Quinella several times, Quinella realized that the sub process has become a threat and resorted to freezing her own emotions via manipulating her own Fluctlight to prevent the sub process from taking control.This plan succeeded and the sub process was made powerless for the next 50 years.

When Quinella discovered that her own mind had reached its limits, she planned to have unimportant memories erased. Originally, the girl whom Quinella chose as her vessel for the backup of her memories was the daughter of a furniture shop owner who became a nun due to her above average system access authority. She was brought to the Axiom Church by Quinella, and had her Fluctlight overwritten with Quinella's own memories and information. However, as Quinella and the nun awoke and saw each other, their souls started breaking down due to the realization of them being identical beings. The nun's soul was the first to break down and, in this moment, the Secondary Core programming of the Cardinal System, took over the girl's mind. With the realization of Quinella being the main process in her own body and the young girl's body being controlled by Cardinal, the sub-process, the two souls stopped breaking down. At that moment, a battle between the two began, with Cardinal having struck first, therefore gaining the advantage. However, when it became clear who the winner would be, Quinella casted a ceremony that blocked access to «Sacred Arts» commands within the room, and produced a weapon. In this way, though the two were equal in almost every way, Quinella had the advantage of reach due to the girl's body being shorter than Quinella's.

Cardinal decided to flee, and took residence within a Library which Quinella created. The Library itself, although initially part of the Central Cathedral, had fluctuating coordinates, residing within the "unused space" of Underworld. After destroying the only entrance, there was no way for Quinella to enter. Then began the process of recording and erasing her own memories, to make room for more information.

She waited in the library for over 200 years, sending familiars to all the human territories to look for possible allies, who had a Transgression Quotient high enough to break the taboos and high enough OC and SC values to be able to fight against the Integrity Knights and Quinella. Although there were several people who fit the description, Cardinal was never able to get to them before Quinella did. She was about to lose hope until she heard that two youngsters had cut the unfellable Gigas Cedar. She immediately sent her most trusted familiar in the area, Charlotte, to look for them. Through Charlotte she discovered that Kirito was a real human, thus she realized that he'd be immune to Quinella's Fluctlight altering commands, and decided to bring him to the Library at all costs.

When Kirito and Eugeo escape from the prison under the Cathedral, she guides them through Charlotte to a door she opened and transports them to the Library where she resides. She allows Eugeo to take a bath and read the books about the story of the Human World to keep him busy while she tells her story to Kirito.

Later she instructs Kirito and Eugeo about using the «armament full control» art and devise their plan to take on Quinella.