Aoi Haruto functions as a tactical instructor and handler at Mihama Academy, repurposed to train elite operatives for the anti-terror organization SORD. His youthful appearance contrasts with extensive field experience gained through prior involvement in CIRS, where he retains active connections. Significant memory gaps and incomplete records obscure his past, though it emerges he was artificially engineered using DNA from Asako Kusakabe and Yuuji Kazami.

Recruited into the covert Phantom Trigger program as a child, he operated as a soldier, forging exceptional combat proficiency—particularly with a non-traditional Japanese sword. He avoids firearms, demonstrating marked ineptitude that some speculate is intentional. During missions, he primarily directs strategy rather than engaging directly. Physically, he has blue eyes, hip-length blue hair, and an androgynous, slim build, inviting peer-like teasing from students. He exhibits minimal culinary interest, typically consuming only salads.

His demeanor radiates warmth and gentleness, yet he engages in mischief, especially teasing Tohka Shishigaya. He adopts a fiercely protective stance toward students, shifting to lethal efficiency when they are threatened. Key relationships include a brotherly dynamic with Murasaki Ikoma, who has known him since childhood, and a mentor-protegé bond with Rena Fukami, his designated firearm handler.

Critical developments unfold during confrontations with antagonists Kuroe and Enishi. In one outcome, he suffers fatal gunshot wounds but eliminates both adversaries using Rena's gun as an improvised shield. Alternatively, he enacts vengeance for his master's death, symbolizing closure by cutting his hair. During these clashes, his demeanor transforms: he ties back his hair and projects an intimidating aura. His tactical choices, including sword preparation, indirectly steer mission outcomes.