"D.C.III ~Da Capo III~" is a manga series that serves as a sequel to the "Da Capo" visual novel franchise, set 20 years after the events of "D.C.II." The story unfolds on Hatsunejima, a fictional island where cherry blossoms bloom year-round due to the influence of a magical sakura tree. The narrative centers on Kiyotaka Yoshino, a high school student who lives a relatively ordinary life until he encounters a mysterious girl named Himeno Katsuragi. Himeno claims to be a descendant of the Katsuragi family, who once protected the island's magical sakura tree. Her arrival sets off a chain of events that intertwines the past and present, revealing the island's hidden secrets.

Kiyotaka becomes involved in the mysteries surrounding the sakura tree and its connection to the Katsuragi family. As the story progresses, it becomes clear that the tree holds immense power, capable of granting wishes but at a great cost. Himeno, along with other characters such as Sara Rukawa, a cheerful and energetic classmate, and Ricca Morizono, a reserved and studious girl, play pivotal roles in uncovering the truth about the tree and its impact on the island's inhabitants. Each character has their own motivations and personal struggles, which are gradually revealed as the plot unfolds.

The narrative explores themes of love, sacrifice, and the consequences of tampering with supernatural forces. Kiyotaka's relationships with the female characters deepen, leading to emotional conflicts and difficult choices. The story also delves into the history of the Katsuragi family and their duty to protect the sakura tree, shedding light on the events that shaped the island's present. As the characters confront their pasts and face the challenges posed by the tree's power, they must decide whether to uphold tradition or forge a new path.

The manga maintains a balance between lighthearted moments and dramatic tension, blending slice-of-life elements with supernatural intrigue. The interactions between the characters drive the plot forward, creating a dynamic and engaging narrative. The resolution of the story ties together the various threads, offering closure to the characters' arcs while leaving room for reflection on the themes explored throughout the series.