Hugh Anthony Disward, known as Huey, is the grandson of bibliomaniac Wesley Disward. Born into the envious, scheming Disward clan, their plots isolating his wealthy mother led Hugh to live primarily with his father in the capital, visiting his mother at Wesley's mansion on weekends. During these visits, his mother sometimes dressed him as a girl named Antoinette Disward to model her fashion designs.

As a child, Hugh displayed calmness, kindness, and a love for books, especially detective novels. He explored Wesley's mansion extensively with his childhood friend Kamilla Sauer Keynes, uncovering its secret passages. He developed an early fascination with airplanes inspired by his father's models and drawings, though he lost respect for his father after witnessing his failure to protect Hugh's mother from family intrigues. Dressed as Antoinette during one visit, he encountered a time-traveling witch who threatened him until Dalian intervened. Dalian lent him a golden key to access the Dantalian's Bookshelf, where he met a girl in white and promised to free her, subsequently forgetting this event until adulthood.

After his mother's death, Hugh served as a Pilot Officer in the Royal Air Force during the Great War. Initially arrogant and focused on combat achievements, his perspective shifted after befriending Flight Lieutenant Ilas Alcock, who emphasized the joy of flying over killing. Ilas's death deeply affected Hugh. Ilas was later resurrected by an antagonist called the Professor, forcing Hugh to confront him as the enemy pilot "Faceless Ghost." Hugh defeated Ilas in a dogfight but discarded his medal for the action, reflecting his disillusionment with war.

Following the war, Hugh inherited Wesley's estate and the guardianship of the Dantalian's Bookshelf upon agreeing to care for Dalian, the vessel of the phantom library. He became her key-keeper, responsible for sealing dangerous Phantom Books containing forbidden knowledge. Hugh and Dalian investigate incidents involving these books, consulting a used bookstore owner for information and assisting police in book-related cases. Hugh uses Wesley's revolver but prefers non-lethal methods in confrontations.

Hugh exhibits patience and dedication in his responsibilities, tolerating Dalian's rude behavior and whims while managing tasks like driving, cooking, and book organization. He maintains a calm demeanor but acts decisively to protect Dalian, often carrying her or using hand-to-hand combat when necessary. Despite his aristocratic background, he performs manual labor uncommon for his social class, such as fixing his car. He avoids discussing his wartime experiences and rejects military titles, identifying simply as a former pilot.

In an anime-exclusive incident, Hugh confronted the Professor during a zombie outbreak linked to the Book of Atonement. After being wounded, he entered the Dantalian's Bookshelf to rescue the girl in white, reinforcing his childhood promise. He later destroyed the zombies using a Phantom Book, aided by fellow key-keeper Hal Kamhout.

Manga-exclusive stories reveal additional facets: During an illness, Hugh hallucinated Dalian commanding shadow creatures, blurring his perception of reality. In another case, he and Dalian encountered Rasiel and the Professor during a mission involving the Book of Wisdom. Hugh demonstrated resourcefulness by using the Phantom Book "An Immortal Wizard" for flight during a tower confrontation.

Hugh's development shows a consistent commitment to protecting knowledge and others, shaped by familial neglect, wartime trauma, and his bond with Dalian. His unresolved promise to free the girl in white from the library remains a driving motivation.