Hogni Ragnar is a dark elf and a first-class executive of the Freya Familia, regarded as one of the most powerful adventurers in the city of Orario. Before joining the familia, he lived a very different life as the king of the dark elves on the island of Hjaðningavíg. His rule, however, was not born of ambition but of circumstance; he was the strongest among his people and was thrust into the role, a position that brought him little joy and constant pressure. Consumed by fear of his own people's gazes and weary of his responsibilities, he eventually encountered the goddess Freya, who promised to liberate him. This liberation came at a catastrophic cost, as Freya instigated a devastating war between his dark elf kingdom and the white elf kingdom ruled by his future comrade, Hedin. The conflict annihilated both nations, leaving Hogni and Hedin as the sole survivors. After three days of fighting each other, Freya appeared before them, revealing her role in the destruction. In response, both warriors chose to follow her, leaving their old lives behind to become adventurers.

Physically, Hogni is notable for being the only dark elf introduced in the series to date. He possesses tanned skin, silver hair that can appear pale purple, and grayish-green eyes, with his hair often covering his right eye. He typically wears a black outfit complemented by a black cloak.

Hogni's personality is a complex mix of deep-seated insecurity and fierce loyalty. He is defined by a crippling social anxiety, having developed an intense fear of being watched by others due to the relentless pressure he felt as king. He finds solace only in darkness, where he believes no one can see him. This anxiety manifests in a peculiar way: he speaks and acts with severe chuunibyou tendencies, affecting a grandiose and delusional manner of speech. This is largely a coping mechanism to mask his profound shyness and social awkwardness, though it often makes him come across as strange or comical to others. In battle, despite his incredible power, he is known for a cowardly disposition, often hesitating or showing fear. He is, however, absolutely devoted to Freya, willing to carry out any order she gives. He was initially jealous of Bell Cranel due to the intense personal attention he received from Freya, viewing the young adventurer as a rival. As this jealousy fades, it gives way to a genuine, if awkward, respect and care for Bell, whom he finds to be a kind-hearted and refreshing presence.

Hogni's central motivation is his unwavering service to Freya, whom he credits for his freedom. He seeks to prove his worth as her executive and struggles with his own internal weaknesses to fulfill her will. As a member of the Freya Familia, he plays the role of a powerful enforcer and guardian, often acting in concert with Hedin, with whom he forms the renowned duo known as the Black and White Knights. Their relationship is a cornerstone of his story; once mortal enemies who fought for three days straight, they have become grudging rivals and mutually respected comrades. While Hogni harbors a fervent desire to eventually defeat Hedin in combat, they fight seamlessly alongside each other. His relationship with Bell Cranel is also significant. Initially hostile due to jealousy, Hogni's perspective changes after interacting with Bell. He eventually begins to train him, during which Bell's earnest and non-judgmental nature helps bridge Hogni's social anxieties, leading to a bond of friendship that surprises even Hogni himself.

Throughout the story, Hogni shows subtle but clear development. He begins as a figure defined by jealousy and social paralysis, but through his encounters with Bell, he starts to step outside his shell. He begins to question the harsh methods of his comrades, showing concern for Bell's well-being, and ultimately makes the monumental decision to betray Freya alongside Hedin. This betrayal comes after realizing the true nature of Freya's actions, deciding to fight for what he believes is right, even against the goddess he is sworn to serve. This arc demonstrates a shift from a follower seeking liberation, to a warrior who can act on his own convictions.

As an adventurer, Hogni is a Level 6 magic swordsman of immense skill. While many elves excel in magic, Hogni is a prodigy with the blade, recognized by Hedin as the most skilled melee fighter among all elves. His hand-to-hand combat prowess is considered among the best in the Freya Familia, the strongest familia in Orario. He is a master of the simultaneous chant, a high-level technique allowing him to cast spells while engaged in close-quarters combat. He wields a cursed longsword named Victim Abyss, which has the property of invisibly extending its blade length at the cost of consuming more of his stamina.

His magic is unique and formidable, with his signature spell being Dainsleif. This short-chant magic does not boost his physical parameters but instead overwrites his personality, transforming him into a ruthless, ideal version of himself as a warrior. It removes his mental limits and cowardice, allowing him to fight with absolute efficiency and brutality. He also possesses Burn Dain, a short-chant explosion magic that unleashes a blast of flames from his arm at close range, useful for attack or creating a smokescreen. A third spell, Rasu Dain, is also part of his arsenal. His skills and development abilities, including Fairy Nocturne and Hunter, further enhance his combat capabilities. His abilities, honed from a lifetime of warfare even before receiving a falna, make him one of the most dangerous and respected first-class adventurers in the world.