Emi Kaidou is a seventeen-year-old high school girl living in the bustling Shibuya district of Tokyo. Her home life is marked by absence and loss; her mother has passed away, and her father has been gone for ten years without explanation, leaving her to live alone in a large apartment. This profound abandonment has left her feeling deeply listless and disaffected, leading her to go through the motions of daily life with a brittle, apathetic exterior. In her more vulnerable moments, she struggles with suicidal thoughts and has been known to engage in reckless, daredevil behavior, almost as if challenging the world to follow through on her despair.

Despite her emotional withdrawal, Emi possesses a sharp mind and a natural curiosity, particularly for mechanical objects. She has a hobby of taking things apart to understand how they work, and she is often able to reassemble them in better working order than before. This tinkering has also fostered in her a talent for drawing, which serves as her primary creative outlet. Emi’s role in the story is catalyzed by the arrival of a mysterious artifact known as the Case. In her hands, it transforms into an oversized, almost childish-looking Possibility Pencil, an item that reflects her desire to draw and has the power to make wishes come true. When her life is threatened, her desperate wish for a hero summons four legendary champions from alternate dimensions: Gatchaman, Tekkaman, Casshan, and Hurricane Polymar. Initially, Emi is reluctant to be involved with these heroes or the battle they represent, viewing their optimism and drive as foreign to her cynical worldview.

Her central motivation evolves from simple survival and indifference to a desperate need to confront the villain, Z, who is ultimately revealed to be her estranged father, Kazumichi Kaidou. This revelation reframes her entire journey, turning an external conflict about saving the world into an intensely personal struggle about family, abandonment, and understanding the past. Her relationships with the four heroes are pivotal to her development. Ken Washio, the hero Gatchaman, serves as her primary emotional support, consistently reminding her that she is no longer alone and helping her break through her emotional isolation. Casshan helps her process her difficult feelings about her father, while Tekkaman offers logical explanations and Hurricane Polymar provides a connection to her own world. Together, they act as surrogate father figures and mentors, slowly teaching her that her life has value.

Over the course of her journey, Emi undergoes significant development. She begins as a withdrawn and suicidal girl who has given up on the world, but through her trials and the bonds she forms with the heroes, she gradually learns to open up, to care, and to fight for something beyond herself. Her final confrontation with Z requires her to use this newfound emotional strength not just to battle a villain, but to reach the heart of the grieving father who disappeared from her life, demonstrating how much she has grown. Emi’s most notable ability stems from her Possibility Pencil. While its full power is mysterious, its primary function is to grant wishes. It is this ability that allowed her to summon the four heroes to her world and, at times, can provide them with power-ups or create objects from her drawings. Beyond the pencil, her own resourcefulness, mechanical aptitude, and her growing emotional resilience become her true strengths.