"Sola" is a 13-episode anime series that blends elements of romance, fantasy, and drama. The narrative centers on Yorito Morimiya, a high school student with a passion for photography, particularly capturing the sky. His life takes an unexpected turn when he encounters Matsuri Shihou, a mysterious girl who avoids sunlight and carries a large katana. Matsuri reveals herself to be a "yaka," an immortal being who sustains her existence by consuming the life force of others. Despite her nature, Yorito becomes drawn to her, and their relationship deepens as they spend time together.

The story explores themes of immortality, loss, and the fragility of human life. Matsuri's past is gradually unveiled, revealing her connection to Yorito's childhood and his sister, Aono Morimiya, who has been bedridden for years due to an unspecified illness. Aono harbors a secret: she is not Yorito's biological sister but a yaka created by Matsuri's brother, Takeshi Shihou, who seeks to manipulate events for his own purposes. Takeshi's motivations are tied to his desire to end Matsuri's immortality, believing it to be a curse.

As the plot unfolds, Yorito discovers his own connection to the supernatural world. He learns that he is not entirely human but a creation born from Aono's memories and desires, designed to replace the original Yorito, who died in a tragic accident years earlier. This revelation forces Yorito to confront his identity and the nature of his relationships with Matsuri and Aono.

The series builds toward a climactic confrontation between Matsuri, Takeshi, and Yorito, as their intertwined fates come to a head. The resolution is bittersweet, with sacrifices made to protect those they care about and to find closure for their unresolved emotions. The ending emphasizes the transient beauty of life and the importance of cherishing fleeting moments, tying back to Yorito's love for the ever-changing sky.

Key characters include Yorito Morimiya, the earnest and kind-hearted protagonist; Matsuri Shihou, the enigmatic yaka with a tragic past; Aono Morimiya, Yorito's "sister" who hides her true nature; and Takeshi Shihou, the antagonistic figure driven by a mix of love and resentment toward Matsuri. The series balances its supernatural elements with emotional depth, creating a poignant exploration of love, identity, and the passage of time.