Kazuo Hagiwara is a young man who serves as a central catalyst for the events of the story. He is a student who managed to flee from Sankou Academy, a private school located on a remote island known as Hell's Castle. The school is secretly ruled by a terrorist headmaster who aims to brainwash students into becoming loyal agents for a fascist coup. Hagiwara's escape sets the plot in motion when he literally bumps into the story's protagonist, who is living a normal life after retiring her role as a special agent.

His background is directly tied to the horrors of the academy, which he describes as a place that turns delinquents into obedient soldiers through brutal training methods and electroshock torture, sometimes resulting in student deaths. He has a close friend named Kikuo Kato, who failed to escape from the island and remains a captive at Sankou Academy.

In terms of personality, Kazuo is presented as a desperate individual trying to survive and seek help. His primary role in the narrative is to inform the protagonist about the true nature of Sankou Academy and to motivate the mission to rescue the students. He delivers a rope doll to a girl named Megumi Kato as a final gift from her captive brother, Kikuo, which inspires her to join the fight against the school.

His character development is tragically cut short. While attempting to fight back against the forces of the academy, Kazuo is killed during an attack by a helicopter sent by the headmaster. He dies shielding the protagonist from the gunfire before she can destroy the aircraft with her weapon, marking his death as a significant emotional turning point that signals the seriousness of the threat. Beyond his role as an escapee and a sacrificial figure, there is no further information available regarding his personality, motivations, or specific abilities.