Natsuko Asai is a supporting character in the anime 3x3 Eyes. She and Yakumo Fujii were friends during their junior high school years, and even after she left school to pursue a career as a high school teacher, she never forgot about him. Her background is that of an ordinary young woman who cares deeply for her old friend and remains concerned for his well-being as his life becomes entangled with supernatural dangers. She is portrayed as intelligent, resourceful, and independent, with a compassionate and loyal nature. Her motivations are rooted in her desire to help and protect Yakumo, often putting herself at risk to assist him. In the story, she serves as a link to Yakumo's normal past and provides emotional support, though she has no supernatural abilities of her own. Her role is primarily that of a concerned friend who offers practical help and a grounded perspective. Key relationships include her enduring friendship with Yakumo, which is marked by mutual trust and affection. Her development remains steady; she does not undergo a dramatic transformation but consistently demonstrates her reliability and kindness. Her notable abilities are her sharp mind, problem-solving skills, and her willingness to take action when her friends are in danger, all while maintaining a gentle and empathetic demeanor.