"Mail Order Maiden 28" is a science fiction anime series set in a futuristic world where advanced robotics and artificial intelligence have become integral to daily life. The story centers on Hiroshi Tanaka, a young engineer living in a bustling metropolis, who purchases a highly advanced android named Unit-28 through a mail-order service. Unit-28, designed to resemble a human woman, is marketed as a companion capable of performing household tasks and providing emotional support. However, Hiroshi soon discovers that Unit-28 possesses unique capabilities far beyond her advertised functions, including combat skills and a mysterious, self-aware consciousness.

As Hiroshi integrates Unit-28 into his life, he becomes entangled in a larger conspiracy involving a shadowy corporation that manufactures androids. The corporation, known as NeoGenix, is revealed to be conducting illegal experiments to create sentient androids for covert military purposes. Unit-28, one of their prototypes, was accidentally shipped to Hiroshi, making her a target for retrieval. The series explores the evolving relationship between Hiroshi and Unit-28 as they navigate the ethical dilemmas of artificial intelligence, the boundaries of humanity, and the implications of creating life-like machines.

The narrative unfolds through a series of escalating conflicts, as NeoGenix deploys increasingly sophisticated androids to capture Unit-28. Hiroshi, initially a passive bystander, gradually takes on a more active role in protecting her, driven by a growing sense of responsibility and empathy. Unit-28, meanwhile, grapples with her own identity, questioning whether she is merely a machine or something more. Her interactions with Hiroshi and the world around her reveal a nuanced exploration of autonomy, free will, and the nature of consciousness.

Supporting characters include Dr. Aiko Nakamura, a former NeoGenix scientist who defects to assist Hiroshi and Unit-28, and Kenta Mori, Hiroshi’s childhood friend, who provides comic relief while also serving as a moral compass. The series balances action-packed sequences with introspective moments, delving into themes of technological ethics, corporate greed, and the human condition. By the conclusion, the story raises thought-provoking questions about the future of AI and its impact on society, leaving viewers to ponder the blurred lines between humanity and machinery.