Moko serves as the protagonist's best friend throughout all series iterations. Her consistent design features long black hair in braids secured by large bows, dresses paired with long socks and Mary Jane shoes. Early manga chapters depict her eyes as monochromatic and shiny, while some anime adaptations and later manga redraws show them with visible sclerae. Originally introduced in the manga as Tomoko Ina, her name evolved during production to Motoko Naniwa (frequently shortened to Moko), inspired by the creator's first wife. This name change carried into subsequent anime adaptations and revised manga runs. Her personality varies across eras: the 1960s version portrays her as relatively level-headed despite occasional physical outbursts, while 1980s and 1990s adaptations heighten her aggression and combativeness. This evolution maintains her role as the more tomboyish counterpart to the variably characterized protagonist. Moko struggles academically, particularly in mathematics, with instances of scoring zero on tests. Her significant physical prowess sees her readily engage in confrontations, embodying a "cute bruiser" archetype. Though she often treats her younger brother Kankichi harshly through verbal scolding or physical discipline, she exhibits a strong protective instinct when he faces genuine trouble, reflecting classic sibling dynamics balancing annoyance with underlying care. Her presence extends beyond the core series via Fujio Akatsuka's "Star System," appearing in works like *Osomatsu-kun* (manga and 1966 anime), *Furious Ataro* (1969 anime), and various one-shot manga stories. While Moko does not appear in the 1990 *Furious Ataro* adaptation, a counterpart character named Himeka Ayanokōji fulfills a similar narrative role.