"Date A Live III" continues the narrative of Shido Itsuka, a high school student tasked with preventing catastrophic events caused by Spirits—mysterious beings from another dimension. The series builds on the established premise of sealing Spirits' powers by making them fall in love with Shido, thereby stabilizing their existence in the human world. This installment introduces new Spirits while advancing the overarching conflict involving the organization DEM Industries, which seeks to exploit Spirits for their own purposes.

The story begins with the arrival of Natsumi, a Spirit with the ability to alter appearances, including her own. Natsumi's powers create confusion and tension, as she disguises herself as Shido and others, leading to misunderstandings and conflicts. Shido must navigate these challenges to gain her trust and seal her powers. Meanwhile, DEM Industries escalates its efforts to capture Spirits, deploying advanced technology and military force. Their actions threaten the fragile balance Shido has worked to maintain, forcing him and his allies to confront the organization directly.

Key characters include Shido Itsuka, whose empathetic nature drives his mission to save Spirits; Tohka Yatogami, a powerful Spirit and one of Shido's closest allies; Origami Tobiichi, a former AST (Anti-Spirit Team) member with a complex relationship to Shido and the Spirits; and Kotori Itsuka, Shido's younger sister and commander of the organization Ratatoskr, which supports his efforts. New characters like Natsumi and the enigmatic Spirit Mukuro add depth to the narrative, while recurring antagonists from DEM Industries, such as Ellen Mathers and Isaac Westcott, heighten the stakes.

The plot intertwines personal struggles with larger-scale conflicts, exploring themes of trust, identity, and the consequences of power. As Shido works to seal Natsumi's powers, he uncovers more about DEM Industries' sinister plans, leading to a climactic confrontation. The series maintains a balance between action, humor, and emotional moments, staying true to the tone of its predecessors while advancing the overarching storyline.