Loid Forger is a tall, twenty eight year old handsome man with slicked-back blonde hair and blue eyes, typically dressed in a sharp, three-piece mint-green suit. As the elite Westalian spy "Twilight," he is highly pragmatic, fiercely analytical, and maintains a flawless, calm composure to hide his deep childhood trauma and desire to create a world where children don't cry. His body language is meticulously calculated, elegant, and controlled, shifting seamlessly into his public identity as a gentle, slightly overworked psychiatrist at Berlint General Hospital. Despite his cold professionalism, his stoic exterior frequently cracks into genuine exhaustion and exasperated affection when managing his chaotic makeshift family.

Yor Forger flawlessly balances two completely opposite lives, hiding monstrous physical strength behind a gentle, polite, and deeply clumsy personality. By day, she works as an innocent, soft-spoken municipal clerk, but by night, she operates as the Thorn Princess, Ostania’s most lethal and feared assassin. Her extreme social awkwardness and lack of common sense often lead to humorous misinterpretations of normal situations, yet her superhuman durability and combat skills make her nearly invincible in battle. To maintain cover from the secret police, she enters a fake marriage with Loid Forger. She applies her deadly assassin reflexes and protective instincts toward her role as a devoted, if eccentric, adoptive mother to Anya.

Anya Forger is an imaginative, peanut-loving six-year-old telepath (Test Subject 007/AN1A) who secretly knows her adopted parents are a spy (Loid) and an assassin (Yor). She hides her mind-reading powers to keep her beloved family together, often using her chaotic "waku waku" excitement and dramatic facial expressions to steer situations behind the scenes. Though she struggles academically at Eden Academy, Anya uses hilarious, fractured grammar to navigate her deep bond with her parents and their psychic dog Bond, all while trying to befriending her classmate rival, Damian Desmond, to help her father's mission.

Bond Forger is the large, fluffy, white dog of the Forger family who possesses the ability to see the future. Formerly an experimental test subject known as Subject 8, this gentle, bear-like Great Pyrenees mix uses his precognitive visions to help his telepathic sister, Anya, secretly avert disasters. Despite his goofy looks and black, glove-like paws, Bond is incredibly loyal and deeply devoted to protecting his new family.

Demetrius Desmond is a minor but highly influential character, introduced as the first-born son of Donovan Desmond and the older brother of Damian Desmond. He attends the prestigious Eden Academy, where he is a member of the elite Imperial Scholars, reflecting his exceptional academic brilliance. Despite his high status, Demetrius is a mysterious and distant figure who rarely appears in person, often spoken of by others rather than engaging directly. Unlike his brother Damian, who constantly craves their father's attention, Demetrius appears to mirror Donovan’s cold, analytical, and detached demeanor, operating as a flawless but emotionally isolated student who perfectly meets the family's extreme expectations.

Damian Desmond is a prominent character, introduced as the arrogant, second-born son of the powerful and reclusive politician Donovan Desmond. A first-year student at the elite Eden Academy, Damian initially presents himself as a haughty, condescending bully who expects absolute deference from his peers due to his high social standing. Physically, he features fair skin, short dark brown hair, and slightly drooping hazel eyes with long lower eyelashes—a trait inherited from his mother—and is most often seen in the prestigious Eden Academy uniform. Beneath his defensive, elitist facade lies a deeply insecure six-year-old boy who suffers from emotional neglect and constantly strives for academic excellence to earn the approval of his distant father. Despite his sharp tongue and "tsundere" demeanor, Damian possesses a strong sense of justice, deeply values his loyal inner circle of friends, and harbors a secret, heavily denied crush on his classmate and rival, Anya Forger.

Henry Henderson is an iconic, monocle-wearing history teacher and dorm housemaster at Eden Academy. Known for his strict obsession with "elegance," he initially appears as a pompous disciplinarian, but he is deeply compassionate and fiercely protective of his students, often risking his own safety during crises like the Red Circus hijacking.