"Ane Log" centers on the daily lives of three sisters and their interactions with their younger brother, Mizuto. The eldest sister, Moyako, is a college student with a strong, domineering personality. She often teases and bullies Mizuto, masking her genuine care for him behind a facade of mockery. The middle sister, Ajimi, is a high school student who is more reserved and introverted. She harbors romantic feelings for Mizuto, which she struggles to express due to her shyness and the complexities of their sibling relationship. The youngest sister, Tsukasa, is an elementary school student who is cheerful and innocent, often serving as a mediator between her siblings.

The series explores the dynamics of their relationships, blending comedy with moments of emotional depth. Moyako's overbearing nature frequently leads to humorous situations, particularly when she tries to assert her dominance over Mizuto. Ajimi's internal conflict and her attempts to navigate her feelings for Mizuto add a layer of tension and introspection to the narrative. Tsukasa's presence often lightens the mood, providing a contrast to the more intense interactions between her older sisters and Mizuto.

The plot unfolds through a series of episodic vignettes, each focusing on different aspects of the siblings' lives. These vignettes highlight the quirks and flaws of each character, creating a relatable and often humorous portrayal of family life. The series does not follow a linear storyline but instead offers snapshots of their daily experiences, emphasizing the bonds and conflicts that define their relationships. The interplay between comedy and emotional moments creates a balanced narrative that captures the complexities of sibling dynamics.