Selka Zuberg is a supporting character in the fourth arc “Alicization” of Sword Art Online, known as the younger sister of Alice Zuberg and a talented but insecure apprentice sacred arts user in the Underworld.
Selka Zuberg is a resident of Rulid Village in the Human Empire of the Underworld.
She is the village elder’s daughter and secretly harbors feelings for Eugeo.
She first appears at about 12 years old, five years younger than her sister Alice Zuberg.
Her daily life revolves around studying sacred arts at the local church and caring for orphans.
Selka struggles with the fact that she cannot use sacred arts as skillfully as Alice.
This inferiority complex shapes many of her decisions and her growth throughout the story.
Her voice actor in the anime adaptation is Kaori Maeda.
Selka is kind-hearted, dutiful, and deeply compassionate.
She takes care of orphans at the church, showing a strong nurturing side at a very young age.
She is also introspective and self-critical, especially when comparing herself to Alice.
Her inability to match Alice’s sacred arts talent leads her to question her own worth and courage.
Despite her insecurities, Selka possesses remarkable bravery.
She proves capable of risking her own life to save others, especially Eugeo and Kazuto Kirigaya (Kirito).
She is quietly in love with Eugeo, admiring his gentle nature.
This affection motivates some of her boldest actions, such as following the trail that leads her toward the End Mountains.
Background and Motivation
Six years before the main events, Alice was taken away to the Central Cathedral in the capital as a sinner.
Selka only later learns the real reason for this from Kirito, after Eugeo confides in him.
Hearing the truth, Selka becomes desperate to understand her sister’s actions.
She wants to know whether she could ever have been a “replacement” for Alice, or if she lacks the courage to break taboos the way Alice did.
To test herself, Selka decides to go as close as possible to where Alice crossed the border.
The next morning, she enters the End Mountains alone, hoping to approach the Dark Territory side.
Kidnapping by Goblins
In the End Mountains, Selka encounters goblin scouts from the Dark Territory.
She is captured and taken hostage.
Kirito and Eugeo rush to her rescue after discovering her disappearance.
They find the goblins, engage them in battle, and successfully free Selka.
During the fight, Eugeo is gravely injured and left near death.
Selka, terrified but determined, uses a high-risk, advanced sacred art to share her own Life (vitality) and Kirito’s with Eugeo.
This Life-sharing ritual is an extremely dangerous technique for someone of her level.
However, she manages to fully restore Eugeo’s Life, saving him at the cost of severe strain on herself and Kirito.
Kirito’s “Oath of the Swordsman”
On the eve of Kirito and Eugeo’s departure from Rulid to become swordsmen, Kirito tests a theory about his own possible duplication.
He believes that if Selka were a copy of him, she would be bound by a self-imposed restriction he places on her.
Kirito gives Selka an “Oath of the Swordsman,” a kind of self-constraint.
Because Selka is able to break through this test condition, Kirito concludes she is not a copy but an independent, genuine person.
In the anime adaptation, this introspective scene is omitted.
Instead, a new scene is added where Selka speaks to Eugeo on the morning of his departure, encouraging his resolve to rescue Alice as a swordsman.
Reunion with Alice and Protecting Kirito
After Quinella’s defeat, the Human Empire is in chaos, and extremists inside the Axiom Church target Kirito.
Alice, now an Integrity Knight, flees to Rulid Village with the unconscious Kirito to protect him.
Selka reunites with her sister after many years of separation.
Despite the villagers rejecting Alice and Kirito because of their strange circumstances, Selka does not turn her back on them.
Together with the elder Garitta, Selka helps shelter Alice and Kirito in a forest near the village.
She supports Alice emotionally and practically while they remain in hiding.
Dark Territory Assault and Farewell
When forces from the Dark Territory attack, Rulid and the surrounding areas are drawn into the conflict.
Alice eventually decides to return to the front lines and fight in the Interworld War.
Selka watches her sister depart again, this time not as a “sinner” but as a protector.
They part with the mutual promise that they will see each other again once the war is over.
After the war and the resolution of the Interworld conflict, Alice departs the Underworld to visit the real world.
Selka, remaining behind, joins the Axiom Church as an apprentice sacred arts user, dedicating herself to study and preparation for the distant future.
Development of Freezing Techniques
With Alice gone to the real world, Selka focuses on finding a way to ensure long-term stability of Fluctlights.
Her goal is to prevent data loss and fragmentation so that reunions with people like Alice remain possible.
Working together with Auyha Fria, Selka first reconstructs a basic Life Freezing Sacred Art.
This technique can suspend a person’s Life to preserve their Fluctlight over long periods.
Their ultimate objective, however, is to recreate the more advanced Petrification Freeze Sacred Art, including its thawing counterpart.
This is based on the original technique created by Quinella but is not perfectly identical.
Because their reproduced ritual differs in details from Quinella’s original, there may be unforeseen side effects.
For that reason, Selka’s version is not used on knights previously frozen by Quinella or Chudelkin to avoid potential complications.
Both the freezing and unfreezing incantations are extremely long and complex.
Reciting a full ritual takes close to one minute, making it a serious commitment in any situation.
Long-Term Preservation and Waiting
Around Human Empire Calendar Year 390, Selka, Ronye Arabel, and Tiese Schtrinen choose to undergo Life Freezing themselves.
All three are in their mid-twenties at the time.
At that point, the full Petrification Freeze Art has not yet been recreated.
They enter long-term suspended animation using the Life Freezing technique as a temporary measure.
Over many decades of research and experimentation, the Petrification Freeze Art is finally brought back.
By Human Empire Calendar Year 441, the ritual is stable enough to be performed.
Selka elects to undergo the Petrification Freeze Art in the Floating Garden of the Central Cathedral.
Ronye and Tiese volunteer to be frozen alongside her, believing it would be too lonely for Selka to wait alone for centuries.
All three willingly accept petrification and deep freeze, entrusting their future to the hope of Alice’s eventual return.
They remain in this state for roughly 200 years, their Fluctlights protected from decay.
Awakening and Reunion with Kirito and Alice
In Star King Calendar Year 582, Kirito returns to the Underworld from the planet Admina.
He brings back a sealed box containing the key to undo the Petrification Freeze Art.
Guided by Eolline Haerents, Kirito once again climbs the Central Cathedral.
He locates the sealed garden where Selka, Ronye, and Tiese are held in stone-like stasis.
Using the key from the sealed box, Kirito successfully deactivates the ancient freezing ritual.
Selka awakens after two centuries of frozen time, physically unchanged but in a completely transformed era.
Upon awakening, she finally reunites with Alice, the sister she has been waiting to see again for hundreds of years in Underworld time.
This reunion fulfills the promise they made around the time of the Underworld War and closes a long emotional journey that began back in Rulid Village.
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