Momoko Ryugasaki is the central protagonist of Kamikaze Girls. She is a high school student who lives in the rural town of Shimotsuma after her father, a former yakuza member, was forced to flee their hometown due to legal trouble involving counterfeit merchandise. Momoko is a self-described Rococophile, deeply obsessed with the aesthetics of eighteenth-century French Rococo and the Sweet Lolita fashion subculture, particularly the brand Baby, the Stars Shine Bright. She is initially dismayed to discover that Shimotsuma lacks any Lolita boutiques, forcing her to travel to Tokyo to satisfy her fashion desires.

Momoko’s personality is marked by a cynical, detached, and often selfish outlook. She is highly intelligent and articulate, with a sharp, straightforward way of speaking. She holds a strong aversion to men, regarding them as crude and unpleasant, and prefers to keep to herself. She is driven by the pursuit of personal happiness and a luxurious, leisurely lifestyle free from obligation. This hedonistic philosophy leads her to con money from her father and spend it entirely on clothing and accessories that align with her Rococo fantasy. Despite her self-centered tendencies, she possesses a keen eye for detail and a natural talent for embroidery, a skill she developed as a hobby.

Her role in the story is as the first-person narrator and the catalyst for the central friendship. The plot is set in motion when she begins selling her father’s counterfeit Versace clothing to earn spending money. Her first customer is Ichigo Shirayuri, a rough, boisterous member of the all-female biker gang the Ponytails. Initially, Momoko sees Ichiko as a nuisance and looks down on her, but their repeated interactions gradually reveal a genuine bond. Their relationship becomes the heart of the story, transforming Momoko from a solitary figure into someone who can care for another person, even if she expresses it in her own peculiar way.

Momoko’s key relationship is with Ichigo. While she often treats Ichiko with condescension, she also shows loyalty and concern. She embroiders Ichiko’s biker coat free of charge, supports her when she is heartbroken over a romantic rejection, and ultimately rescues her from a gang confrontation by throwing her grandmother’s scooter and water balloons at the bikers, causing them to flee. This act demonstrates a hidden protective streak and physical resourcefulness despite her delicate appearance. She also interacts with her parents, whom she regards with disdain: her father she calls “the Loser,” and her mother she sees as superficial. Her connection with her grandmother is more positive, as she lives in her house.

Over the course of the story, Momoko undergoes subtle development. She begins as a completely self-absorbed loner who believes that personal happiness is the only meaningful goal. Through her friendship with Ichiko, she learns to act selflessly and to value someone else’s well-being. When the owner of Baby, the Stars Shine Bright offers her a job as an embroiderer, she declines, choosing instead to become Ichiko’s manager, prioritizing her friend’s budding modeling career over her own comfort. This decision marks a significant shift from her earlier attitude.

Notable abilities include her exceptional embroidery skill, which catches the attention of a major fashion brand owner. She is also a highly knowledgeable expert on Rococo history and fashion production. A more unusual trait is her electromagnetic energy field, which causes pachinko machines to give her constant jackpots, providing her with a steady income. Additionally, she displays surprising physical strength, capable of lifting and hurling a moped with ease. These abilities, combined with her sharp intelligence and unwavering commitment to her own vision of beauty, make her a memorable and unconventional lead.