Iska

The protagonist of this work is a young soldier belonging to the Empire, aged 16. He wields a special pair of swords called "Star Swords," one black and one white, and is known as the "Successor of Black Steel." The black Star Sword can block any astral spirit art, and the white Star Sword has the ability to replicate any astral spirit art blocked by the black one just once. This ability is unique to Iska and cannot be mass-produced. Aliceliese perceives these swords as similar to the chains that bind the progenitors. Their true nature is not as swords, but as "vessels" made from "Star Crystals" that have been purified and forged to their limits, intended for all astral spirits to return to the core of the stars.

Iska climbed to the highest military rank of "Apostle Saint" in the Empire's army at the youngest age in history, but was stripped of his title for aiding the escape of a certain astral spirit user. Although Iska and Aliceliese recognize each other as worthy rivals, they often find themselves in situations where they must cooperate ambiguously, despite their similar tastes in food and art.

They frequently encounter each other in a neutral city, and as they continue to fight together ambiguously, their awareness of each other as rivals fades, and they begin to develop romantic feelings for each other as members of the opposite sex. However, Iska prioritizes his mission as the Successor of Black Steel and the peace between the two nations, remaining unaware of his own feelings.

Furthermore, the witch he helped escape, who triggered his title revocation, turns out to be Sisbell, Aliceliese's sister. Sisbell also harbors feelings and expectations for him, and like her sister, attempts to scout him along with his unit, but he naturally refuses for the sake of his own aspirations. However, he ends up saving her again, unintentionally deepening her affection for him, and temporarily takes on the role of guarding her unit using Mismis's astral crest as a bargaining chip.

Iska is also the object of obsession by the sisters, leading to conflicts with the eldest sister of the Lou family, Iriarte, and even with members of the Zoa and Hydra families like Kissing and Mizelhibii, inadvertently attracting the interest of all the princesses of the enemy royal families.

Although he appears mild-mannered, he is actually very stubborn and persistent. He has a strong sense of purpose to forcibly bring about peace between the Empire and the Imperial Court by capturing pure-blooded witches, earning him the ironic nickname "Combat-Hating Berserker." Because of his ideals and determination, he bluntly refuses the invitations of Aliceliese and Sisbell.

On the other hand, he cannot overlook the method of imprisoning even weak astral spirit users, leading him to rashly aid their escape, which ultimately results in him losing his position as an Apostle Saint and being sentenced to life imprisonment, a situation that even Jhin points out as lacking in big-picture thinking. However, Crosswell, his mentor, had chosen Iska as his successor knowing full well that this temperament would lead to such outcomes, and when he heard about the actual prison break, he affirmed, "That's fine for you."

Trained intensively by Crosswell to specialize against astral spirit users, Iska displays sword skills so divine that Jhin asserts, "If the opponent is an astral spirit user, he will not lose." However, his talent with the sword is not innate but the result of relentless practice and dedication.

However, because he specializes in fighting astral spirit users, he has not received training in personal combat, and if he were to engage in melee combat, even among Apostle Saints, he would likely remain at a mid-level at best, never reaching the top. He self-assesses that he would fall behind in the first or second strike when competing against Johaim, the top-ranking Apostle Saint who also wields a sword.

After repelling an attack by Vispose, Iska successfully brings Sisbell to the central state, but gets entangled in Iriarte's schemes and is forced to accompany her to the Lou family's villa. There, Iriarte's hatred for the Imperial Court is jokingly revealed, which later turns out to be true, deeply shocking him.

During an attack on the Imperial Court by the Empire, disguised as Empire soldiers, Iska engages in combat with Talisman and others from the Hydra family. Moreover, the intrusion of the escaped Vispose leads to Sisbell being kidnapped, and during the pursuit, he unfortunately encounters Aliceliese. Despite her tears and hatred for the Empire, he decides that it is not the time to settle things and reveals Talisman and Iriarte's schemes, also clearing up misunderstandings through a message from Yumirisha's "Resonance" astral spirit.

Later, with the help of Yumirisha and others, Iska infiltrates Hydra's research facility "Snow the Sun." There, he battles the Hydra princess Mizelhibii and obtains a fragment of her earring, the "Gregorio Secret Script." From there, it is revealed that Sisbell's destination is the Empire, and they decide to return to the Empire, with Rin assisting in her rescue by following them.

Initially, Rin's cooperation was merely tacit approval as he happened to discover and rescue Sisbell. However, the possibility that the place where she was held was an illegal research facility prompts Iska and his team to intervene as Empire soldiers. Although they find Sisbell, they also discover a furnace storing multiple artificial astral spirit energies, unveiling the dark side of the Empire. Furthermore, the researcher overseeing the research room "Elsa's Coffin," Kelvina, performs a malignant astral mutation similar to Vispose and attacks, but Rin's cooperation and a stroke of luck help them defeat her. However, Lisha, accompanied by the celestial emperor Yunmelungen, appears and detains Rin, leaving him shocked by the emperor's true identity and puzzled by the invitation to the imperial capital.

However, due to the aforementioned incident, the Eight Apostles deem him too knowledgeable and secretly decide to execute him. He is then attacked by the giant star soldier possessed by the Eight Apostle Lucrezeus at the Glasnacht research facility. With the cooperation of Lisha, Sisbell, and the 907th unit, they manage to defeat him, but this leads to a complete hostile relationship with the Eight Apostles.

Later, upon reaching the imperial capital, Iska reunites with his mentor Crosswell and is told to meet with Yunmelungen.

Before meeting Aliceliese on the battlefield, Iska had encountered her once before, and that experience led him to realize that astral spirit users are different from what is taught in the Empire.