"Girly Air Force" is set in a world where humanity faces an existential threat from mysterious flying creatures known as Zai. These entities, also referred to as "Xi," are highly advanced and possess technology far beyond human understanding. To combat this threat, nations develop advanced fighter jets piloted by artificial intelligence units called "Daughters." These Daughters are humanoid in appearance, designed to resemble young women, and are paired with human pilots to enhance their combat effectiveness.

The story centers on Kei Narutani, a young man who dreams of becoming a pilot. After a chance encounter with a Daughter named Gripen, who saves him during a Xi attack, Kei becomes deeply involved in the fight against the Zai. Gripen, a highly advanced and independent Daughter, forms a bond with Kei, and the two begin working together. Kei joins the military to support Gripen and other Daughters in their missions, driven by a desire to protect humanity and uncover the truth behind the Zai.

As the narrative progresses, the series explores the dynamics between humans and Daughters, highlighting the ethical and emotional complexities of their relationships. Gripen’s unique personality and growing attachment to Kei add depth to their partnership, while other Daughters, such as the stoic Phantom and the cheerful Eagle, contribute to the team’s efforts. The military’s strategies and technological advancements play a significant role in the ongoing battle, with the Zai’s origins and motives remaining a central mystery.

The series balances action-packed aerial combat with moments of character development, focusing on the bonds formed between the human pilots and their AI counterparts. Themes of trust, cooperation, and the blurred lines between humanity and artificial intelligence are woven into the narrative. As the conflict intensifies, Kei and Gripen face increasingly dangerous missions, culminating in a climactic confrontation that tests their resolve and the strength of their partnership. The story leaves room for exploration of the Zai’s true nature and the future of humanity’s coexistence with Daughters.