"Strawberry Marshmallow" (Ichigo Mashimaro) is a slice-of-life comedy anime centered around the daily lives of a group of young girls and their humorous, often mundane adventures. The series primarily focuses on the interactions between the main characters: Nobue Itou, a laid-back high school student, and her younger sister Chika, along with their friends Miu Matsuoka, Matsuri Sakuragi, and Ana Coppola.

Nobue, the eldest, often finds herself reluctantly dragged into the antics of the younger girls, despite her attempts to maintain a more mature demeanor. Chika, her younger sister, is quiet and responsible, often acting as the voice of reason among the group. Miu, the most energetic and mischievous of the group, frequently stirs up trouble with her impulsive behavior and overactive imagination. Matsuri, Miu's best friend, is shy and reserved, often serving as the target of Miu's teasing. Ana, a British exchange student, adds a unique dynamic to the group with her limited understanding of Japanese culture and language, leading to many comedic misunderstandings.

The narrative unfolds through a series of episodic vignettes, capturing the girls' everyday experiences, such as going to school, playing games, or simply hanging out at Nobue's house. The humor arises from the contrast between the characters' personalities and their reactions to ordinary situations, often escalating into absurd or exaggerated scenarios. Miu's schemes, in particular, frequently disrupt the group's routine, leading to chaotic yet lighthearted outcomes. Despite the comedic tone, the series occasionally touches on themes of friendship, family, and growing up, though these moments are subtle and never overshadow the overall lighthearted atmosphere.

The anime maintains a gentle, whimsical tone throughout, with a focus on character-driven humor rather than a continuous plot. The interactions between the girls highlight their distinct personalities and the dynamics of their relationships, creating a charming and relatable portrayal of childhood and adolescence. The series is notable for its simplicity and warmth, offering a nostalgic and endearing look at the small, everyday moments that define the lives of its characters.