Mayumi Takahashi is a young first-year student at Sparta Academy, a boarding school run by corrupt and sadistic teachers who derive pleasure from torturing and humiliating their female students. She is portrayed as an innocent and good-natured girl, though she is somewhat dimwitted. Her poor academic performance often results in her being sent to the school's torture chamber, where she faces humiliating punishments. Just when the teachers are about to go too far, she is rescued by a mysterious female superhero known as Kekko Kamen, who appears in a revealing costume consisting only of a mask, boots, gloves, and a scarf. The constant rescues have filled Mayumi with a deep sense of affection and gratitude toward her mysterious protector, and she frequently wonders about the true identity of the masked heroine. Mayumi's role in the story is that of the primary victim and damsel in distress, whose misadventures drive the plot and provide the reason for Kekko Kamen's intervention. Her key relationship is with Kekko Kamen, whom she views with admiration and longing. Mayumi does not demonstrate any notable combat abilities or special skills; instead, her main function is as the innocent target of the school's abusive faculty. The story focuses on her suffering and subsequent rescue, with her character remaining largely static throughout the narrative.