Kirito and Eugeo just barely hold their own against Eldrie Synthesis Thirty-One, who is armed with all manner of magical attacks and divine objects. They’re only able to escape defeat when Eugeo suddenly remembers why Eldrie seems so familiar: he used to be Eldrie Woolsburg, the North Empire representative swordsman.
Hearing his former name and other details of his past, a triangular prism is slowly ejected from his forehead, and the former Eldrie’s personality seems to return. The transformation is interrupted by an attack by a second knight armed with a bow and riding a dragon, but the implication is clear: what happened to this guy must’ve happened to Alice. The person she used to be might not be gone; only repressed.
Kirito and Eugeo would have probably eventually been caught by the second knight, but are given yet another break when a voice tells Kirito which way to turn and presents them with a glowing secret doorway through which to dive.
They land at the bottom of a stair, before a diminutive-looking sage called Cardinal. She is the Cardinal System that once governed the Underworld, but she’s been usurped, and her powers are now limited to the great library that contains all of the world’s knowledge and history.
Upon showing the boys around, she sends a sneezing, soaked Eugeo off to the bath to warm up, and summons some food and tea for Kirito. The balance of the episode is Cardinal (voiced, I think, by Tange Sakura, complete with “umus”) basically delivering a lengthy infodump, focusing on her “twin elder sister”, Administrator, the self-made Pontifex of the Axiom Church and only one who can contact the outside world.
“Administrator” was once Quinella, the offspring of the first political marriage between high lords, and the descendant of one of the “original four” inhabitants of Underworld who, unlike the other three, was driven by greed and a lust for power. Quinella was gifted with System Call, and used it to hunt animals and gain more and more authority.
Eventually, she had her followers, upon whom she demonstrated various “miracles”, build her a church in which she still resides to this day, being worshiped and ruling with absolute authority. She solidified that authority by writing the Taboo Index, which forbade the very actions that gave her the power boost she needed to seize command of the world.
Even Quinella couldn’t initially win against the ravages of time, but even on her death bed never stopped trying to find the right commands to undo her demise. She succeeded, either due to coincidence or help from the outside world, and her fluctlight was augmented with the Cardinal System as it was to create a new, no longer “human” being, naming herself “Administrator.”
Suffice it to say, Admin is one tough cookie. Considering how badly Kirito fared against a novice Integrity Knight, he and Eugeo are going to have to seriously up their game if they want to overthrow her. I daresay it wouldn’t hurt to snap Alice out of her brainwashing (Eugeo knows far more of her past than of Eldrie’s) so she could fight beside them.
But I’m just spitballing at this point. The villain has been introduced and explained. Now we’ll see what the heroes are going do about it.