At age ten, Karna enters the Spirit World during a rare planar alignment, bypassing the frantic rush of her peers. While other children scramble for minor companions, Karna walks deep into the desert to reconnect with Gemini, a unique spirit capable of copying the abilities of others. On her way, elemental spirits present her with a heavy request: several powerful, ancient reincarnators are illegally tapping into the elemental planes, threatening to destabilize the multiverse. In exchange for hunting them down permanently, Karna demands and receives an orb containing the purest seeds of all elements. To begin her path, she must awaken her dormant Phoenix bloodline. Arjuna takes her to the caldera of an active volcano, where she sits in a specialized fire formation. As she activates her Aura, the heat intensifies into a plasma maelstrom, burning away all mortal impurities. A heavenly tribulation of fire crashes down, but instead of destroying her, she absorbs the celestial energy to form her second magic circle, massively expanding her core. She briefly manifests as a giant electric-blue phoenix before returning to human form, physically aged up to look like a thirteen-year-old. This sudden physical and magical leap forces her to buy an entirely new wardrobe with Duskclaw, but it also prepares her to dominate the Academy entrance exams. She shatters the previous records, scoring nine hundred and sixty-three points in the combat test without even using a focus, which instantly marks her as a target for the Academy's elite factions. During her physical training class, she refuses to use her powers, easily outlasting her classmates in a grueling endurance run. When the arrogant Leonin student Brimaz challenges her to a hand-to-hand duel, Karna uses her fluid, river-like fighting style to dismantle his defenses, ending the fight with a devastating counter-punch to his midsection. This public display of martial supremacy cements her position at the top of class I-1, but it also triggers a wave of jealousy that leads to a mysterious break-in at her dormitory.

The mystery of the dormitory break-in deepens when Karna discovers a magical recording of an older student named Mint, a Changeling sent to test her by a secret student council. Rather than being rattled, Karna uses the incident to strengthen her defenses and focus on her next major milestone: the Titan Awakening. Her classmate Siegfried, the older son of the warrior Wolfgang, warns her that this secret council is tied to the shadowy political factions of the Magocracy and advises her to refuse their recruitment. Following his advice, Karna rejects the invitation, choosing instead to focus on her cultivation. To awaken her Titan bloodline, she needs a place rich in metal and lightning energy. Arjuna takes her to the mountain lair of Llethunaxx, a greedy blue business-dragon who agrees to help in exchange for having gold coins poured over his scales. As Karna activates her Aura, the storm above the lair escapes the dragon's control, raining down divine swords and lightning. She fully awakens her Celestium Titan bloodline, absorbing the tribulation energy to form her third magic circle. Her skin gains a metallic, organic sheen harder than steel, and she physically grows to the height of a fifteen-year-old. This massive discharge of divine energy alerts the nearby Holy Knights of the Sacred Dynasty, who arrive to investigate. Arjuna and Llethunaxx successfully bluff the knights, but the encounter highlights the growing instability of the neighboring theocracy. Soon after, the Dynasty's rulers are executed by divine immortals for conspiring with the Underworld, causing the theocracy to collapse and sparking a massive regional war. The Magocracy mobilizes its fleets to secure the borders, drawing Arjuna away on military campaigns. Amidst this geopolitical chaos, Tsumi, the Academy's Headmistress, offers Karna a way to escape the political fallout: a diplomatic mission and tournament on the wintry world of Frostpeak, where Karna will finally confront another powerful reincarnator.

Arriving on the icy world of Frostpeak, Karna finds herself surrounded by the elite students of the multiverse. Among the crowd, her sharp soul-senses detect two other reincarnators: a young Yuki-Onna girl named Mayumi and an arrogant Djinn warrior who views other reincarnators as prey. During the non-combat demonstrations, Karna takes the stage and requests a random element, performing a breathtaking blade-dance with True Light magic, or Qhaysh. Her movements draw an intricate eighth-circle spell of Unmaking into a storage gem, leaving the master of the Luminous Sect in absolute awe. This display provokes the hostile Djinn reincarnator into challenging her to a duel in the arena. The boy unleashes green ki palms and Efreeti fire, but Karna's pure mana and Phoenix affinity easily neutralize his attacks. When he attempts a forbidden soul-strike, he leaves himself completely exposed. Karna catches his soul, suppresses the attack, and summons Gemini in the form of a massive, golden-armored archangel to deliver a crushing blow. Following her victory, she privately comforts the confused Mayumi, explaining the rules of memory retention and the River of Souls. She also confronts her former disciple from a past life, Stormcaller, who is now terrified of her wrath and promises to spy on the rogue reincarnators stealing elemental power in exchange for her mercy. Upon returning to the Academy, Karna and Tsumi decide to punish the boys who tried to peep on them in the hot springs by making them kneel in front of the cafeteria. To protect Karna from the newly arrived Divine Emissary, Prince Tethrine, who bears a striking resemblance to her, Tsumi hastens a diplomatic mission to the High Elven Court. Karna, Miralen, Shaheera, Sieg, Travan, and Mayumi set out across the wilderness, heading toward the ancient elven city of Teleriand, where a grand festival of life will force Karna to test her newly matured body.