Frequently appearing to be lethargic, sleepy, and unmotivated, Ryner is the protagonist of the story. He has brown eyes and hair and is of slender build; is naturally talented in magic, hand-to-hand combat, arts of assassination, ancient lore, languages and symbols, and the bearer of Alpha Stigma, an ocular ability which grants him the ability to analyze various forms of magic. Alpha Stigma bearers when activating their powers, have a pentagram with reddish hue appearing over their pupils. Because of this ability, in a world where magic forms differs from country to country and is a closely guarded secret, he has learned and acquired magic originating from different countries through battles with their mages. Although the Alpha Stigma are the weakest and most common type out of the five types of "Cursed Eyes," primarily because the bearers don't live to adulthood to fully utilize their potential before they are slain after going berserk usually at a young age, Ryner's eyes are no ordinary Alpha Stigma.

Ryner Lute's real name is Feruna Lutelu, and was born of the Noble House of Lutelu, but because of a pact made with “The Goddesses," a collective legendary power of existences that devours everything, he lost his memories of his childhood, including his real name and the names of his birth parents. He has been known as "The Strongest Mage of Roland" within the military since the age of thirteen, after defeating Kuwonto Kuo, who previously held that title. However, because of a lack of intention to kill, he seldom fights at full strength. His magical prowess does not stem solely from his Alpha Stigma, and he was judged by his master Germer as one who possesses a natural high level of comprehension ability and an acute sense in magic. Because of Germer's hellish training which led to serious sleep deprivations, Ryner was always looking for opportunities to catch up on his sleep whenever there was nothing to do, which later became more of a habit than a necessity.

Alpha Stigma bearers are often shunned and called "monsters" as once they go berserk and lose their sanity, they will start killing and destroying indiscriminately and never to return to their senses again. Ryner is thus grateful towards Sion, Ferris, and Kiefer because of their acceptance of him as a human being despite their awareness of him being an Alpha Stigma bearer. Moreover, he is regarded as an anomaly because he is the only person to have been able to regain his sanity after losing control of his Alpha Stigma. As such, even after going berserk and killing many innocent, he was allowed to live as a rare research subject. He also carries half of the essence ("The Lonely" portion) of the legendary demon lord known as "The Lonely Demon," which was implanted by his own father, Lura, in order to save him from what would normally be the doomed fate of an Alpha Stigma bearer.

Ryner has a tendency to distance himself from others because he does not wish to cause harm and grief to others due to his eyes and vice versa. He has caused multiple girls throughout his life to fall in love with him, though he is reluctant to love again after his first love sacrificed herself to save him. That's what he thought until he met Ferris, whom he began to have strong feelings for and with whom he formed a strong bond.

Undertaking a quest from his trusted friend and the new King of Roland, Sion, and in the company of swordswoman Ferris, he travels across the continent of Menoris in search of the "Relics of Heroes," legendary artifacts later more accurately and collectively known as "Rule Fragment" and "Rule Phajeel"The undertaking was a result of his own research report into the "Relics of Heroes", with the vision of creating a world with no wars and conflicts. After he returns from his quest, he notices a greater power eating into Sion from within. He eventually unravels a series of conspiracy throughout Roland and its neighboring countries, and discovers a greater force at work. Later, after being betrayed, and with the desire to save his friends, he escapes Roland with Ferris, carrying the hope that Sion can still be saved, eventually traveling with the Anti-Roland Coalition.

During the battle between Gastark and Geihlficlant, while on the verge of death after losing his Alpha Stigma and arms to Ril, Ryner fully awakens as "The Solver of All Equations". His Cursed Eyes becomes its true form, appearing as a rainbow-colored blinking tear-shapes over his eyes. This not only grants him the ability to analyze the structure of magic, but also that of human beings and other physical materials as well, and these include the "equations" (a.k.a structures) of "Rule Fragment" or the "Relics of Heroes". He also acquires the ability to traverse into the spirit plane at will. When fully activated it allows him to deconstruct infinite numbers of any object living or inanimate at will, but it requires the sacrifice of the soul belonging to a loved one. And it was revealed to him by his father later on, that the soul of his mother had been the sacrifice during the awakening.