"Taimanin Asagi" is set in a dystopian future where humanity coexists with demons, and a specialized group of warriors known as Taimanin are tasked with maintaining order and combating supernatural threats. The narrative centers on Asagi Igawa, a highly skilled Taimanin who serves as the series' protagonist. Asagi is dedicated to protecting humanity from demonic forces, often engaging in intense battles that test her physical and emotional limits. Her younger sister, Sakura Igawa, also plays a significant role, sharing a similar commitment to their mission but often finding herself in precarious situations due to her inexperience.

The story begins with Asagi and her allies investigating a surge in demonic activity linked to a powerful organization called the Kurokawa Syndicate. This criminal group seeks to exploit the chaos caused by the demonic incursions for their own gain. Asagi's journey intertwines with the lives of other Taimanin, including Rinko Akiyama and Murasaki Yukikaze, each bringing their unique abilities and personal struggles to the fight. The series explores themes of loyalty, sacrifice, and the moral complexities of battling evil in a world where the line between right and wrong is often blurred.

As the plot progresses, Asagi faces increasingly formidable adversaries, including powerful demons and traitorous humans who seek to undermine the Taimanin's efforts. The narrative delves into her internal conflicts, particularly her struggle to balance her duty with her personal desires and relationships. The series also highlights the bonds between the Taimanin, emphasizing their camaraderie and shared resolve in the face of overwhelming odds. Through its action-packed sequences and character-driven storytelling, "Taimanin Asagi" presents a tale of perseverance and resilience in a world teetering on the brink of chaos.