Kaori Iba serves as the homeroom teacher for Class 2-B at Aoi Academy, the class attended by the main characters Kazuki Shikimori, Yuuna Miyama, and Maiho Kurioka. This particular class is regarded as the worst in the school, and Iba is the instructor responsible for managing it.

Her personality is defined by an all-consuming passion for video games. She dedicates so much of her resources to purchasing game software that she struggles to afford proper meals, and she has even attempted to convince a game shop owner to let her buy items on credit. This consuming hobby contrasts sharply with her past, as she was once a mercenary of formidable power. During her time as a mercenary, she was known as a vampire by her associates and enemies, a reputation that led to rumors about her being a supernatural being among her fans. In the first encounter with her student Maiho Kurioka, Iba demonstrates her combat prowess by successfully fighting and defeating multiple armed terrorists while protecting the girl. Within the story, her role extends beyond that of a simple teacher, as she exists to monitor and protect the main group of characters.

She harbors a strong dislike for the school doctor, Haruaki Akai, though there are indications of a potential romantic connection between them. Her physical appearance includes red eyes and short, maroon or burgundy-colored hair. Her birthday is May 5.