July Andou is the main protagonist of the story, a fifteen-year-old student at Senko Private High School and a member of the school's Literature Club. His given name derives from the month of his birth. Andou is an eccentric and energetic young man, tall with unruly black hair and teal-green eyes. He typically wears the standard school uniform paired with a distinctive red coat, often pulling up the right sleeve to use his supernatural ability.

His personality is defined by a pronounced and unapologetic case of chuunibyou, a tendency to indulge in grandiose, fantasy-inspired delusions. He refers to himself by the alias Guiltia Sin Jurai, speaks in dramatic, overwrought phrases, and frequently poses as a dark anti-hero from his imagined mythos. While this behavior often exasperates his friends, it is not a sign of immaturity in other areas; Andou is surprisingly perceptive and academically capable, earning decent marks in his classes. Beneath his edgy exterior, he possesses a genuinely kind, compassionate, and understanding nature. He is loyal to his friends, often serving as the emotional anchor of the group. When serious situations arise, he can drop his chuunibyou persona and demonstrate a calm, tactical, and unexpectedly mature mindset, assessing problems with a level head.

His motivations are not driven by the desire for conflict or glory, but by a wish to cherish and protect the mundane, happy days he shares with his clubmates. He values his identity and his unique power, no matter how weak, as a part of himself. A formative incident during his middle school years, involving a silver-haired girl named Tomoyo, inspired him to continue his delusional lifestyle, teaching him to accept the faults of others and fostering his carefree outlook. This same period also left him notably oblivious to the romantic affections that several of his female club members develop for him, a blind spot rooted in his past experiences.

Within the Literature Club, Andou acts as a central and unifying figure. His unwavering kindness and willingness to listen make him a source of support for the others, even as his chuunibyou antics are a constant source of gentle annoyance. His key relationships include a deep, lifelong friendship with Hatoko Kushikawa, who has known him since childhood and often bears the brunt of his eccentricities. He shares a more intellectual and chuunibyou-affirming bond with Tomoyo Kanzaki, while he also has a caring senpai-kouhai dynamic with the club president, Sayumi Takanashi, and a protective relationship with the younger Chifuyu Himeki.

Over the course of the story, Andou shows development by confronting the gap between his expectations of a supernatural battle-filled life and the reality of their ordinary days. He learns to navigate the complicated emotions of those around him and, when pushed to his emotional limits, must reconcile his fantasy persona with his genuine feelings and responsibilities toward his friends in the real world.

Andou's unique supernatural ability is called Dark and Dark. It manifests as a small, writhing black flame that he can summon from his right hand. The flame is notably lukewarm, produces no heat, and is incapable of burning anything, making it almost entirely useless in a practical sense. Despite this, Andou treasures his power as an affirmation of his identity. However, his ability possesses a hidden second stage, a desperate measure known as the Dark and Dark of the End, or Dark and Dark Over the End. This evolved form generates a massive, intense, black flame that is incredibly hot and cannot be extinguished by any normal means, including water or other supernatural abilities. This flame poses a lethal danger as it will burn endlessly, even consuming its own user, and the only known way to stop it is to sever the limb from which it originates.