Isaac

Isaac is Est's loyal retainer and Ashe's twin. Introduced as one of two eleven-year-old boys, Isaac is later revealed to be a half-Nymph girl trapped in a male body by a divine curse; after the curse is lifted, the after story identifies her as Aisha. She supports Est as a guard, adviser, scout, fighter, and practical caretaker rather than seeking William's affection for herself. (Chapters 64, 69, 290, 430, and 1464)

Biography

The Trial of Courage and a new ally

Isaac and her twin are trained from childhood to serve Est, and that responsibility governs their journey to Astrid's Trial of Courage. Isaac helps pull Est away from a Mountain Troll, forms a defensive perimeter when danger closes in, and physically stops Est from revealing the kingdom's secret mission after the oracle had ordered silence. When the trial turns into a fight against a Cyclops, Isaac combines Earth projectiles with her twin's Water Magic to hold the creature's attention, then accepts William's dangerous plan because clearing the trial matters more than her initial distrust of his leadership. Their cooperation helps Est finish the trial and changes William from a suspicious stranger into someone Isaac respects. (Chapters 65, 69, 71, and 74–75)

That respect remains distinct from romance. Isaac refuses even a joking opportunity to treat William as a slave because she regards him as a good person, invites him to visit the capital, and consistently mediates when Ashe—then known as Ian—loses her temper with him. At the same time, Isaac never lets friendship displace duty: when William asks her to care for Est, she answers that serving her Young Master is her responsibility. (Chapters 76, 78, 84–85)

Hestia Academy and the Mind Weaver

At Hestia Academy, Isaac becomes an officer of the Magic Division and supplies Est with the measured judgment that complements her quieter manner. She warns that William's proposed wager is dangerous precisely because he has deliberately offered Est an irresistible advantage, correctly reading the offer as evidence of his confidence. That caution cannot protect Isaac from Carter's laced candy, however. The Mind Weaver and Dark Desire spells take control of her, and under Carter's order she knocks Wendy unconscious, helps bring her into the hidden passage, and guards the captive with a weapon drawn. These actions are coercion rather than a chosen betrayal: once Carter's hold breaks, Isaac immediately understands the harm she helped cause. (Chapters 143, 230, 244, 279, 284, and 289)

The aftermath forces several concealed truths into the open. Isaac confirms to Wendy that she is a girl living under the curse, but firmly denies loving William and defines him only as a friend. This separates her path from Est's and Ashe's romantic bond with him and clarifies the role she chooses for herself: supporting her Young Master and twin without competing for their partner. (Chapters 290 and 420)

The Southern Continental War

When an enemy spell turns the adults at Windsor Fortress into crystal, Isaac runs with Est to King Noah and then checks Est's anger when Prince Lionel orders the survivors to prioritize the injured. Her intervention prevents an internal confrontation at a moment when the kingdom can least afford one. Back in Gladiolus, Isaac studies the anomaly that the black-robed men remained unaffected, voices the possibility that the Crown Prince is involved, and makes clear that she would rather be wrong than see that suspicion confirmed. She scouts the city for news and helps Est move the crystal statues of their loved ones before the pair withdraw north, turning her retainer's loyalty into practical crisis management. (Chapters 321, 324, 373, 382, and 418–420)

Reunited with Ashe and William, Isaac is brought into William's inner circle because he expects them to keep fighting together. She chooses that future directly when she declares that she will go wherever Est and her twin go. In the Dungeon of Atlantis she continues training even though she cannot gain System experience as her companions do, accepting Beast Cores instead and treating their growth as an advantage for the whole group. She later stands beside Est during the fighting against the Elves, rides Ragnar in his Grand Cerberus form while fighting alongside Wendy, and helps defend the human city long enough for William's promised return. (Chapters 422, 427, 430, 445, 458, and 489–498)

The curse's end and Aisha's future

Isaac remains in the Hellan Kingdom when duties prevent her and Est from following William to the Central Continent. This makes her restoration dependent on his trials for Aamon rather than on action she can take herself. Aamon eventually unseals the curse after William's battle with Morax in the Deadlands, restoring Isaac's true body and ending the condition that had shaped her public identity since childhood. The source later has Estelle call her restored attendant “Amirah,” while the after story identifies Isaac as “Aisha”; it does not explain the discrepancy. (Chapters 639, 672, 710–711, 951, 1099, and 1145)

In the after story, Aisha remains close to the wider household but finally develops a life not defined solely by attendance on Est and Ashe. She falls in love with Conan's adult form at first sight and confesses before Claire can do so. Rather than turn the situation into a rivalry, Aisha and Claire both become Conan's fiancées; the three deliberately begin as friends and reach a relationship they describe as mutual love and care. Aisha's blunt effort to steer the guileless Conan away from admirers shows that her old protective instinct survives even after her curse and retainer-centered youth are behind her. (Chapter 1464)

Appearance and personality

Under the curse, Isaac appears as an eleven-year-old boy and is repeatedly presented alongside an identical-age twin. Her restored form, called Aisha in the after story, looks almost exactly like Ashe; the explicit difference given there is Aisha's light-brown hair against Ashe's light-blue hair. An earlier account says that the restored twins also differ in eye color, but does not specify Isaac's. (Chapters 64, 69, 1145, and 1464)

Isaac is the quieter and more deliberate of Est's two retainers. Est trusts her habit of planning expeditions, checking supplies, and offering a second opinion, while Isaac is willing to restrain both Est and Ashe when emotion threatens their judgment. Her reserve does not make her humorless: she teases Ashe about her hostility toward William and privately recognizes the source of William's narcissism. She is also domestic and self-sufficient, regularly preparing food and enjoying foraging for ingredients when circumstances allow. (Chapters 71, 76, 78, 151, 373, 420, and 430)

Skills, classes, and divinities

Isaac is a trained close-range guard and Earth-magic combatant whose abilities are shaped by her half-Nymph heritage and Astrid's curse. The corpus demonstrates several applications but does not name a formal Job Class for her or establish a post-restoration rank.

Half-Nymph bloodline and the divine curse

Isaac and Ashe inherit a Nymph bloodline strong enough that they are described as more Nymph than Human and able to assume Human form. The narrative explains that Ashe's Human side converts sealed Spiritual Power into Magic Power and immediately uses this to account for both twins' placement in the Academy's Magic Division; it does not separately detail Isaac's conversion mechanics. Astrid's curse forces Isaac to remain in a boy's body until Aamon unseals it; unlike Ashe, Isaac is not shown temporarily releasing the seal herself, so the limits and mechanics of her original Nymph form remain unknown. (Chapters 289–301, 710, and 1099)

Earth Magic

Isaac uses Earth Magic offensively and defensively. Against the Cyclops, she launches long-range earthen projectiles at its eye in tandem with Ashe's Water Magic; the attacks do not injure the eye, but reliably draw the giant's attention and enable the group's diversion. In the Academy dungeon, Isaac conjures a round shield of Hard Rock about a meter and a half tall, then uses its mass to ram a Hobgoblin Warrior away. These scenes establish ranged shaping and solid defensive construction, but the source does not explain her casting method, mana cost, maximum range, or whether the shield can withstand attacks above that opponent's level. (Chapters 74–75 and 155)

Isaac continues dungeon training after the war, but unlike William's System-linked companions she cannot benefit from distributed experience points. William compensates with high-grade Beast Cores, allowing her to pursue ordinary rank advancement while contributing to group expeditions and large battles. No later chapter provides a named upgrade or demonstrates how lifting the curse alters her Earth Magic, so her latest degree of mastery is not established. (Chapters 422, 434, 458, and 491)

Weapons, fieldcraft, and judgment

Isaac carries daggers or short swords and is trained well enough to fight a Threat Level D (Mid) Hobgoblin Warrior evenly without using magic, treating the exchange as sword practice before switching to her stone shield. Beyond combat, she scouts occupied Gladiolus, plans expedition supplies, cooks for the group, and forages for food. Her most consequential non-magical skill is judgment: she recognizes William's trap in the Academy wager, detects signs of conspiracy after the crystallization spell, and repeatedly redirects Est away from rash disclosure or confrontation. (Chapters 64, 71, 155, 230, 373, 382, 420, and 430)

Astrid's divinity

Isaac is one of Astrid's core followers, together with Est and Ashe. This bond leaves a trace of Astrid's divine power in her soul, but Isaac never demonstrates a distinct spell or transformation fueled by that trace. Astrid remains her patron after the curse is lifted, and Isaac recognizes the goddess when Astrid attends William's wedding. The corpus therefore establishes divine affiliation and a soul-level trace, not an independently usable divine technique. (Chapters 551, 1076, 1206, 1251, and 1422)

Relationships

• Est: Isaac is trained from childhood as Est's retainer and makes that service the center of her early life. She protects Est physically, guards the secrecy of royal missions, advises her against manipulation and conspiracy, and follows her through war and displacement. (Chapters 65, 69, 71, 230, 324, 373, and 430)
• Ashe: Ashe is Isaac's twin, known publicly as Ian while both sisters are cursed. They fight as a coordinated pair, and Isaac often restrains Ashe's temper; separation from her is unusual enough to leave Isaac lonely. After their restoration, they remain close within Estelle's circle, and Isaac is described as looking nearly identical to her sister. (Chapters 66, 74, 244, 430, 1145, and 1464)
• William: Isaac grows from distrusting William to admiring and befriending him, but explicitly rejects the idea that she is in love with him. William values her enough to include her in his inner circle and ultimately fulfills his promise to free her from the curse. (Chapters 75, 84–85, 290, 422, and 1099)
• Astrid: Astrid is Isaac's patron goddess and the source of the curse on her body. Although Isaac remains a core follower with a trace of Astrid's power in her soul, the reason Astrid imposed the curse is not explained in Isaac's own account. (Chapters 295, 551, 1076, and 1422)
• Conan: After her restoration, Aisha falls in love with Conan's adult form and confesses to him. She and Claire become his fiancées, and the three develop their relationship from friendship into mutual commitment. (Chapter 1464)

Items

Isaac uses ordinary daggers and short swords, while her large Hard Rock shield is a product of Earth Magic rather than a separately carried artifact. No independently notable item associated with her is established in the supplied corpus. (Chapters 64, 71, and 155)