"Valkyrie Chōkyō Semen Tank no Ikusa Otome 10-nin Shimai" is set in a dystopian future where humanity faces extinction due to a mysterious alien threat known as the Aegis. To combat this existential crisis, the Valkyrie Project is initiated, creating genetically engineered warrior sisters, each designed to pilot advanced mecha units powered by a unique energy source derived from human semen. The ten sisters, collectively referred to as the Valkyries, are raised and trained to harness their abilities and protect Earth.

The narrative centers on the sisters' struggle to balance their humanity with their engineered purpose. Each sister possesses distinct personalities and combat specialties, reflecting their individual roles within the team. The eldest, Freyja, serves as the de facto leader, embodying discipline and responsibility, while the youngest, Hrist, is more impulsive and emotionally driven. Their interactions highlight themes of familial bonds, identity, and the ethical implications of their creation.

As the story progresses, the Valkyries face escalating threats from the Aegis, whose motives and origins remain shrouded in mystery. The sisters must confront not only external enemies but also internal conflicts, including doubts about their purpose and the morality of their existence. The series explores the psychological toll of their mission, as well as the societal pressures placed upon them as humanity's last hope.

Key plot points include the discovery of a hidden agenda behind the Valkyrie Project, the revelation of a traitor within their ranks, and the gradual unraveling of the Aegis' true nature. The sisters' journey is marked by intense battles, personal sacrifices, and moments of introspection, culminating in a climactic confrontation that challenges their unity and resolve.

The series blends action, science fiction, and drama, with a focus on character development and moral dilemmas. The Valkyries' relationships with each other and their creators are central to the narrative, providing emotional depth amidst the high-stakes conflict. The story ultimately examines themes of survival, free will, and the cost of humanity's reliance on technology and genetic engineering.