Little My lives with her sister Mymble at the Mymble Residence but hibernates at Moominhouse during winters when her sister is absent. She awakens each spring alongside the Moomin family. Physically small with fair skin, green eyes, and ginger hair styled in an onion-shaped top knot, she consistently wears a red smock dress and trousers, often accessorized with a pink ribbon—a look that became iconic across media adaptations.

Her personality blends fierce independence with a love for mischief and chaos. Outspoken and quick-tempered, she delivers blunt skepticism toward others’ plans, like doubting the Snork’s flying ship invention. Despite her size, she fearlessly pursues adventure and competition, such as jumping on magical pink clouds or winning impromptu contests against characters like Sniff.

This adaptation expands her emotional range beyond her original literary portrayal. While retaining core bravery and chaos-seeking traits, she occasionally shows vulnerability: discouragement, remorse when her actions trouble others, or romantic interest in Snufkin—a departure from the books, where romance is absent. The anime also depicts her engaging in traditionally feminine activities like appreciating jewelry or picking flowers, adding depth to her abrasive demeanor. Notably, the familial link from Tove Jansson’s books—where Little My is Snufkin’s older half-sister—is omitted here; they are portrayed as unrelated.

She demonstrates loyalty within her chosen family group, joining activities like hide-and-seek with Moomintroll, Snufkin, Snorkmaiden, and Sniff. Yet she maintains her sharp, independent perspective throughout these shared experiences.