"Anne's Diary: The Story of Anne Frank" is an anime adaptation of the real-life diary of Anne Frank, a Jewish girl who documented her experiences while hiding from the Nazis during World War II. The series chronicles Anne's life from 1942 to 1944, focusing on her time in the Secret Annex, a concealed apartment in Amsterdam where she, her family, and four others lived in hiding to escape persecution.

The narrative begins with Anne receiving a diary for her 13th birthday, which she names "Kitty." Through her entries, the series explores her thoughts, emotions, and observations as she grapples with the challenges of confinement. Anne's vivacious and introspective personality shines through her writing, capturing both the mundane details of daily life and the profound impact of the war on her world. The confined space of the Annex becomes a microcosm of human relationships, tensions, and resilience, as the inhabitants navigate fear, boredom, and the constant threat of discovery.

Key characters include Anne's parents, Otto and Edith Frank, and her older sister, Margot. Otto, the calm and supportive patriarch, plays a central role in maintaining morale, while Edith struggles with the strain of their situation. Margot, quieter and more reserved, contrasts with Anne's spirited nature, creating a dynamic sibling relationship. The Van Pels family—Hermann, Auguste, and their son Peter—also share the Annex, adding layers of interpersonal conflict and camaraderie. Fritz Pfeffer, a dentist and the eighth occupant, further complicates the living arrangements, particularly through his shared room with Anne.

The series delves into Anne's evolving relationship with Peter Van Pels, which transitions from initial awkwardness to a tender connection, offering moments of solace amidst the turmoil. Anne's reflections on identity, hope, and humanity are central to the story, as she dreams of becoming a writer and believes in the inherent goodness of people despite the horrors surrounding her.

Tragically, the Annex is discovered by the Nazis in 1944, leading to the arrest and deportation of its inhabitants. The series concludes with a somber acknowledgment of Anne's fate, as she and most of the others perish in concentration camps, with only Otto Frank surviving. The enduring legacy of Anne's diary, preserved and published by Otto, serves as a poignant reminder of the resilience of the human spirit in the face of unimaginable adversity.