Asami Igarashi is a young girl who becomes closely associated with the Danger Service Agency. She is first introduced as a shy and timid elementary school student, often described as being in the sixth grade. Her home life is marked by the absence of her parents, who are consistently too busy with work to care for her, leaving her alone most evenings. This isolation extends to her school life, where she has few friends and is frequently the target of bullying by her classmates, who extort money from her and subject her to emotional and physical harassment.

Her life changes when she is trapped in an abandoned building by her bullies and becomes caught in the middle of a violent confrontation involving the DSA. Witnessing the combat prowess of Mikura Suzuki, the agency's primary fighter, Asami becomes utterly fascinated. She is inspired by Mikura's strength and confidence, qualities she feels she lacks. This admiration quickly develops into a desire to become strong like her idol, leading Asami to unofficially join the group. Despite the objections of the agency's leader, Kenichi Kurokawa, she begins hanging around the DSA's office every day, determined to learn from Mikura and become a capable agent herself.

Within the story, Asami serves as a witness to many of the DSA's dangerous cases and a developing character who grows from a helpless victim into a more courageous individual. Her primary motivation is to overcome her own fears and weaknesses by emulating Mikura. She observes Mikura closely, hoping to absorb her fighting spirit and resilience. Over the course of the series, she becomes involved in a significant experiment that helps her lose a portion of her fears, and she even learns how to handle a weapon. This development marks a key part of her journey, as she gradually moves away from being a purely timid character.

Her most significant relationship is with Mikura Suzuki, whom she views as a master and role model. This dynamic is the central driving force behind her actions and her desire to be part of the dangerous world of the DSA. She also interacts with the other members of the agency, including the cynical leader Kurokawa and the tech expert Tomohisa Harada, though her primary bond remains with Mikura. While Asami does not possess any superhuman or extraordinary abilities, her notable trait is her latent potential for courage and her determination to grow stronger. Her journey throughout the series focuses on her transformation from a bullied schoolgirl into a more resilient individual who actively seeks to face danger rather than run from it.