Mana Tatsumiya attends Class 2/3-A at Mahora Academy. Her parents manage Tatsumiya Shrine on the campus, where she serves part-time as a priestess and exorcist. She combats supernatural entities using specialized firearms loaded with enchanted spellbreaker bullets. Professionally, she operates as a mercenary, accepting contracts primarily focused on hunting, exorcising, or destroying demons and ghosts, though she undertakes any job offering sufficient financial reward. Her work approach is serious and direct, sometimes perceived as cold or intimidating, contrasting with her typically reserved and unsociable daily demeanor. She exhibits frugality, spending cautiously and seeking discounts. Biologically of mixed heritage, she is half-Puerto Rican and half-Japanese. She carries innate supernatural traits derived from her half-demonfolk bloodline, the source of her abilities. This heritage grants her extended longevity, enabling her to remain alive and physically unchanged into the 22nd century. Her physical characteristics include a height of 184 cm, making her the tallest girl in her class, and measurements noted with decimal precision. Her abilities center on combat and perception. She possesses a "Demon Eye" enabling her to detect demons and spirits, though its sensitivity has limitations. She demonstrates exceptional marksmanship, capable of precise targeting under pressure, such as preventing confessions during the Mahora Festival by rapidly incapacitating multiple individuals with headshots using a sniper rifle. She employs various firearms and specialized ammunition, including time-dilation bullets, storing them extradimensionally via the "Ikuudansou" magic for immediate access. She also utilizes "Rakansen," a technique involving coin-throwing as projectile weapons, shown during the Mahora Martial Arts Tournament against Ku Fei. Within the narrative, she discovers Negi Springfield's secret as a mage during the Kyoto rescue mission involving Konoka Konoe. She participates significantly in the Mahora Festival under contract with Chao Lingshen, tasked with disrupting confessions and later aiding Chao's objective to reveal magic's existence. During this event, she engages in a prolonged sniper duel with Kaede Nagase. Later, during the expedition to the Magic World (Mundus Magicus), she assists Negi's group, Ala Alba, confronting threats like Zazie Rainyday's sister. In this conflict, she reveals her half-demonfolk lineage and deploys time-manipulating bullets. She contributes to the final battle against the Mage of the Beginning. Her long-term story involves continued conflict across global battlefields due to the repercussions of Negi Springfield's post-victory plans. She participates in the 22nd-century Martian War of Independence, an event impacting Asuna Kagurazaka's delayed awakening. Approximately 80 years after the main events, she appears physically unchanged in the sequel UQ Holder!. She assumes the role of acting headmaster at Amano-Mihashira Academy City's magical school, providing guidance to protagonist Touta Konoe regarding the Mahora Martial Arts Tournament as a means to access the orbital elevator. Dialogue implies a past association with the immortal group UQ Holder. She previously formed a Pactio contract with a now-deceased mage resembling the Biathlon Club captain. This contract left her with a Pactio card bearing the name "Mana Arcana" (meaning "secret"). She maintains an implied, unexpressed attraction to the Biathlon Club captain, whom she shot to prevent a confession, aligning with her contracted duties during the festival.