The plot centers around two main characters, Sakura and Nanami, who share a deep, sister-like friendship. The narrative catalyst occurs when Nanami visits Sakura’s household ahead of her friend after finishing a school assignment, inadvertently uncovering a dark, hidden dynamic involving Sakura's father.
Kokoro, the young girl who becomes Aoi's "granddaughter," is a sweet and energetic character who brings a sense of innocence and wonder to the story. Her interactions with Aoi are some of the most delightful moments in the series, as they learn to rely on and care for each other.
The storyline centers around the complex, often dark interpersonal relationships between two childhood best friends and a father figure.