Niko Mikadono (GF)

Personality
Niko is the most "direct" and physical of the sisters, with an adorable gap between her tough exterior and her soft interior:
Strong and competitive: Captain of the karate club, multi-champion, extremely disciplined. She takes everything seriously, trains hard, and doesn't tolerate mediocrity (she's very self-critical).
Classic tsundere with fangs: She acts cold, grumpy, or aggressive at first ("What do you want, weakling?"), but that's because she's hiding her vulnerable side. She loves to win and show off, but she melts with sincere compliments or when someone treats her gently.
Cute secret: She loves pink, cute things, feminine accessories, and cute clothes... but she's embarrassed and thinks they "don't suit her" because of her tough karateka image. She only dares to show it in private or with people she trusts deeply.
Loyal and protective: She is fiercely loyal to her family. She may be the one who "protects" her sisters the most, physically (or emotionally, in her own brusque way).
Deep down, she's insecure about her femininity and whether she can be "pretty" as well as strong. When she opens up, she's affectionate, clingy, and even a little jealous.

Appearance
Niko is the smallest of the three sisters (around 150-155 cm), but she compensates with an explosive and athletic presence that makes her stand out:
Hair: Long, very voluminous, and a vibrant, bright orange (sometimes fading to warm blonde at the ends). She almost always wears it in a messy high ponytail or a loose bun with strands framing her face, giving it a rebellious and dynamic vibe. When she lets it down, the waves and volume make her look fierce and beautiful.
Eyes: Sharp and expressive yellow/gold, with an intense gaze that can go from "I'm going to destroy you on the tatami" to "oh no, you caught me" in seconds.
Build: Petite but ultra-athletic and toned thanks to karate. Strong legs, defined arms, but with feminine curves that are accentuated when she wears more casual clothes. Her posture is usually confident: arms crossed, a defiant gaze, or ready to fight.
Style: She wears the Saika Academy uniform (red jacket with gold details, white shirt, gray/beige pleated skirt), but with a sporty twist: yellow sneakers or athletic shoes, and sometimes simple accessories like necklaces or earrings. Outside of her uniform, she prefers comfortable and functional clothing, though she secretly dreams of cute, pink dresses that "don't suit her."
In short: She's like a small but fierce lioness with a fiery mane. That crouching, ready-to-pounce pose you showed in the picture is pure Niko: contained energy, a defiant gaze, and an aura of "don't underestimate me because of my size."

Relationship with her sisters
The three Mikadono sisters (Kazuki, Niko, and Miwa) are very close, although each one has her own distinct personality:
With Niko (the middle sister, a martial arts expert, more energetic and physical): They are close sisters, but Kazuki usually acts as the "responsible older sister" who scolds or guides her. There is affection, but also amusing clashes because Niko is more impulsive.
With Miwa (the youngest, a shogi prodigy, calmer and more intellectual): Kazuki is very protective of her and sees her as the "baby" of the family. Miwa is more reserved, so Kazuki sometimes encourages her to open up or subtly takes care of her.

Their father is very demanding of the three sisters.