Atsushi Dōjō serves as a First Lieutenant in the Library Defense Force and commands the elite unit known as the Dōjō Squad. Physically, he is notably shorter than many men his age, standing at approximately 165 centimeters or five feet four inches, though this stature in no way diminishes his effectiveness or authority. Despite his compact build, he is highly capable in both combat situations and routine library administrative work.

His personality is characterized by strictness and a straightforward, no-nonsense demeanor. This approach to leadership has earned him the reputation of a demon instructor, as he consistently pushes his subordinates to their absolute limits to ensure they meet the high standards required of the Library Defense Force. Due to his rigid and serious character, he often becomes an easy target for teasing from other officers who find amusement in unsettling his composure. While he is typically calm and collected, this composure falters reliably when the situation concerns a specific subordinate, Iku Kasahara.

Deeply driven by a powerful sense of responsibility and duty, Dōjō’s motivations are rooted in the protection of intellectual freedom and the books that represent it. A pivotal event from five years prior to the series start shaped his present actions and relationship with Kasahara. Touched by a high school girl’s bravery in risking herself to protect a book, Dōjō used his authority as a library officer to demand the censoring agents return the material. Though Kasahara perceived this as a heroic deed that inspired her to join the Library Defense Force, Dōjō’s actions were considered reckless by his superiors. The incident was humiliating for him, subjecting him to numerous trials and the label of being shallow-minded. While he resolved never to act so impulsively again, he also admitted to himself that he did not regret the choice he made that day.

This backstory is central to his role in the narrative, as he is the man Kasahara has idealized as her prince, a fact she does not initially realize when she joins the force. Upon recognizing her during her interview, Dōjō is consumed by guilt, believing that his past actions are responsible for her choosing such a dangerous profession. Consequently, he treats Kasahara with extreme harshness, hoping to make her quit and thereby protect her from the very real dangers of the job. His role is therefore that of a superior officer whose tough exterior masks a deep, personal concern for a subordinate’s safety, while also leading his squad through missions to defend library materials from government censorship, including guarding the only existing copy of a foundational text on library law.

His most significant relationship is, by far, with Iku Kasahara. Despite his attempts to drive her away, Dōjō deeply cares for her, more than for any other subordinate. Over the course of the story, his strict treatment gradually gives way to displays of care and affection. He is known for patting her head when he offers praise or comfort, a gesture that communicates what his stern words often do not. Multiple hints suggest his feelings for her are romantic, and as he becomes kinder, her own feelings toward him evolve in turn. He also shares a close bond with his classmate and best friend, Mikihisa Komaki, with whom he attended the University of the Islands.

Throughout the narrative, Dōjō undergoes significant development. He begins as a harsh and seemingly unfeeling commander, but this is revealed to be a misguided attempt at protection born from guilt. As he witnesses Kasahara’s determination and growth, he starts to accept her choice and becomes more openly supportive, with his natural sense of responsibility shifting from forcing her out to ensuring she is trained and ready for the challenges ahead. His abilities are notable; in addition to his combat prowess, he is a capable leader and administrator, having graduated at the top of his class from the University of the Islands.