Marin is a striking girl with long, pale blonde hair featuring dyed pink tips and framing front bangs, paired with bright, expressive pinkish-red eyes and dark eyelashes. She stands at an average height with a slender, stylish build, and often wears her school uniform—a white button-down shirt worn loosely with the sleeves rolled up, a dark pleated skirt, a loosely tied blue tie, and dark thigh-high socks paired with loafers. Her look is completed with multiple ear piercings, long manicured nails, and various silver rings, perfectly capturing her energetic, fashionable, and unapologetic gyaru aesthetic.

Wakana Gojo is a tall, broad-shouldered high school student with short, spiky black hair, gentle brown eyes, and thin eyebrows, giving him a quiet and mild-mannered expression. Unlike many of his peers, he stands unusually tall at around 185 cm (approx. 6'1") and has a somewhat sturdy frame built from years of craftsman work making traditional Hina dolls. At school, he wears his standard uniform—a neatly buttoned white dress shirt, a slate gray tie, light blue plaid trousers, and brown loafers—though when working at home on doll-making or sewing cosplay outfits, he frequently shifts into comfortable traditional attire, such as a simple dark blue samue (artisan workwear) paired with a headband to keep hair out of his face.

Sajuna Inui, also known by her cosplay name or nickname "Juju," is a petite high school student who looks much younger than her age, standing at just 142 cm (around 4'8"). She has short, pale lavender hair cut in a bob with bangs framing her face, wide red-purple eyes, and a perpetually serious, stoic facial expression. Because of her small stature and youthful features, she is frequently mistaken for a primary school student, which often frustrates her. Her everyday style is neat and modest, typically seen either in her formal, long-sleeved dark school uniform with a white sailor-style collar or in cute, modest casual clothes, contrasting sharply with the intense, professional perfectionism she brings to her high-end cosplay outfits.

Shinju Inui is Sajuna's younger sister, who, in stark contrast to her elder sibling, is exceptionally tall for a middle school student, standing at 178 cm (around 5'10") with a mature, curvy physique. She has short, wavy, dark blue-grey hair styled with soft bangs, large, gentle blue-green eyes, and a noticeably soft-spoken, shy demeanor. Despite being in middle school, her tall stature and soft features often lead people to assume she is much older than Sajuna. Shinju is typically seen in a classic navy-and-white middle school sailor uniform, featuring a dark pleated skirt, white top with a dark collar, and a red neck ribbon, or in oversized, cozy casual clothes that match her modest, introverted personality.

Nowa Sugaya is one of Marin's high school friends, known for her vibrant twin-tail hairstyle with long black hair featuring eye-catching red highlights underneath, complemented by soft bangs, dark eyes, and a playful expression. She has an athletic yet slender build and embodies a fun, edgy gyaru aesthetic, accentuated by multiple ear piercings, dark manicured nails, and a perpetually cheerful smile—often seen enjoying a lollipop. She wears the standard school uniform with a relaxed flair, layering a black sweater vest over a white collared shirt with an unbuttoned collar, paired with a dark necktie, a pleated plaid skirt, and loafers, perfectly reflecting her outgoing, teasing, and friendly personality.

Suzuka Itou is a skilled cosplay photographer in My Dress-Up Darling who supports Marin and Wakana. Recognizable by her closed eyes and dusty blonde bob, she has a calm demeanor that hides a wildly passionate fan identity. She views high-quality cosplay as essential emotional fuel, loves male crossplay, and serves as a mentor who guides Marin on camera gear.

Daia Yahiro is a mature, outspoken high school classmate and friend of Marin Kitagawa in My Dress-Up Darling. Recognizable by her shoulder-length light brown hair, greenish-brown eyes, and black-painted nails, she frequently hangs out with Marin's core friend group at school. She has a grounded personality and is known for providing sharp, witty commentary on the people and events around her.