Momoko Futo stands as the central figure in her series. Her full Japanese name, 富戸 もも子, signifies the family name Futo and given name Momoko, incorporating playful wordplay referencing "thick thighs," aligning with specific physical attributes and comedic situations involving her appearance.

Physically, Momoko possesses long light brown hair, sometimes depicted dark brown, reaching her back. She has black eyes with gray tints and long, thin eyebrows. Her standard attire features a notably short skirt, a gray sweater over a white dress shirt, black stockings or blue tights, and brown shoes. This uniform defines her typical look, though she occasionally experiments, such as wearing Mayumi’s sailor-style uniform or a casual outfit with a black jacket, jeans, sneakers, and scarf, seen in manga chapter 84. She invests considerable time styling her hair in various ways before school.

Her personality is predominantly carefree and mischievous. She approaches daily life with a laid-back attitude, often engaging in spontaneous or unconventional activities without concern for consequences or social judgment. This trait sometimes leads to minor accidents, injuries, or unintended underwear exposure, serving as comedic elements. Despite distractibility and occasional gullibility, she demonstrates determination and curiosity, eagerly pursuing new ideas or adventures. Though her plans often fail due to a lack of follow-through or physical stamina, she remains resilient. She expresses protectiveness and warmth toward close friends, actively including them in activities and valuing their companionship. Her emotional range encompasses excitement, frustration, and empathy, making her relatable despite her quirks.

Key formative events shape Momoko's background. Her astrological sign is Pisces. She befriended Shibumi Shibusawa in childhood after partially repairing a hair barrette broken by other girls during a conflict, initiating their enduring bond. Later, when Mayumi transferred to her school and initially found her intimidating, Mayumi observed Momoko playing with shadow puppets alone and joined in, leading to a quick friendship. Momoko subsequently introduced Mayumi to Shibumi, solidifying their trio.

In daily life, Momoko exhibits creativity and resourcefulness. She invents games or diversions from ordinary objects, like crafting napkin animals at a family restaurant when unable to afford food or using playground chalk drawings for an improvised board game, actions often drawing public attention due to their unconventional nature. Her adventures involve mundane yet comically exaggerated challenges: battling drowsiness in class, attempting skateboarding, exercising, drawing on fogged windows, or seeking shelter from rain. A recurring element is her obliviousness to wardrobe malfunctions, like upskirt moments. Despite frequent minor misfortunes, she navigates experiences with enthusiasm.

Relationships are central to her character. Shibumi, her long-term friend since grade school, shares a history of trust and repair symbolizing loyalty. Mayumi, initially a newcomer, integrates into the group through Momoko’s inclusive and playful initiative. Momoko actively involves both friends in her activities, reflecting her role as the trio’s unifying and energetic force. Family context is occasionally implied through school routines and leisure time.

A notable distinction is her voice, or lack thereof. The series deliberately avoids dialogue, relying on visuals and sound effects. However, in a unique exception during the anime’s final episode, Momoko speaks a single line, marking her as the only character to break this silence.