Ganryū Hanakiri is one of three human lieutenants in the imperial army's Ministry of Spirit Affairs, historically its youngest second lieutenant at age 16. His family background is unknown.

He possesses brown hair and grey eyes. Shy and highly intelligent, he occasionally makes unintentionally inappropriate remarks due to limited experience interacting with girls. He exhibits a Napoleon Complex, reflecting feelings of inferiority about his stature or age. Generally reluctant to act, he proves capable when necessary. His advanced intellect secured his early promotion, though he lacks the combat prowess of colleagues Agemaki and Riken. His most noted skill is uniquely distinguishing the identical half-spirit twins Bonbori and Hozuki solely by their voices.

Assigned as partners to the twins within the Ministry, he forms an immediate close bond. Bonbori and Hozuki frequently cling to him and tease him, causing visible fluster, yet he deeply cares for their well-being. This mutual protectiveness manifests in danger; Bonbori once nearly sacrificed herself for him, and Hozuki physically shielded him. After such a battle, his emotional outburst prompted the twins to confide their traumatic past, signifying profound trust. Their relationship evolves into a romantic OT3 dynamic, culminating in a mutual love confession by the series end.

He interacts infrequently with Agemaki but adopts a younger-brother-like role, offering blunt advice about Agemaki's communications with Zakuro during tense moments. His surname "Hanakiri" combines "flower" (花) and "paulownia" (桐), while his given name "Ganryū" incorporates "round/purity" (丸) and "dragon" (竜).