Shirase Kobuchizawa initially presents herself as cool, serious, and somewhat aloof, but her composed exterior often gives way to intense emotional reactions. Among the group, she is arguably the most passionate and emotionally expressive, frequently overreacting in humorous or heated situations. Her strong reactions make her one of the most dynamic and unpredictable members of the team.

Socially awkward and often misunderstood, Shirase tends to keep to herself, which has led to her being labeled as a loner or “weirdo” by her peers. Her serious attitude and difficulty expressing herself naturally have made it hard for her to make friends. Nevertheless, she is deeply loyal and values the close bonds she forms with Mari, Hinata, and Yuzuki, eventually seeing them as her dearest companions.

Shirase has a deep fascination bordering on obsession with penguins. Her excitement over them often leads to exaggerated physical and emotional reactions, such as heavy breathing, enduring unpleasant smells, or shouting out in excitement. Her enthusiasm for Antarctica reaches comical heights, including a moment where she runs through the snow shouting “Wait for me, penguins!” before crashing into a wall.

Despite being shy and prone to embarrassment particularly with activities like karaoke or appearing on camera Shirase is determined to push through her discomfort. She frequently stumbles during news reports or avoids the camera altogether, but still strives to become someone who can perform confidently, even describing her goal as becoming a “funny, witty camera girl.”

Shirase is also known for her bold and sometimes questionable planning. Early in the series, she jokingly suggests using the appeal of high school girls to charm their way onto the Antarctic expedition. However, the plan collapses due to mutual shyness and her own reluctance to follow through. These moments reveal her impulsive but ultimately innocent nature.

She is highly goal-driven and persistent, often growing frustrated when her plans fail. For example, when her mother’s friend Kanae Maekawa initially refuses to help her join the expedition, Shirase bitterly but determinedly declares that if she had more money, the answer might have been different. Her persistence is evident in her efforts to raise one million yen through part-time jobs to fund her trip, showcasing her dedication and work ethic.

Shirase’s inner strength is a defining part of her character. Though frequently mocked for her dream of reaching Antarctica, she refuses to be discouraged. Instead, she uses that ridicule as motivation to push forward. Her emotional resilience and unwavering pursuit of her goal inspire those around her.

One of her most touching moments of friendship comes when she sees Hinata visibly upset after encountering her former track teammates on television. Despite Hinata putting on a cheerful front, Shirase sees through it and, overcoming her fear of cameras, stands up for her friend by emotionally confronting the girls who once hurt her publicly telling them to “piss off” for making Hinata suffer.

Shirase is a tall, slender teenage girl with hip-length black hair and distinct pink eyes. Her bangs are cut straight across her forehead, and she has an asymmetrical hairstyle where the strand of hair on her left side is longer than the one on the right. Her facial structure is long and defined, and she is the tallest among the four main girls. Shirase often wears a neutral or serious expression, but her face is highly expressive quickly shifting to show emotions such as anger, joy, surprise, embarrassment, or sadness depending on the situation.

By the end of the series, Shirase cuts her hair to neck-length as a symbolic tribute to her late mother, Takako Kobuchizawa.

Shirase is first introduced in her standard school uniform. Her casual outfits often include a black miniskirt paired with mid-thigh-length stockings, reflecting a modest yet fashionable style.

The given name Shirase (報瀬) is composed of the kanji 報 (shira), meaning “information” or “news,” and 瀬 (se), meaning “swift current” or “rapids.”

Her name is derived from the Japanese icebreaker Shirase, which itself is named after the Shirase Glacier. In accordance with Japan Maritime Self-Defense Force (JMSDF) naming conventions, auxiliary vessels such as icebreakers are named after locations of natural beauty or historical importance. The glacier was named in honor of Lieutenant Nobu Shirase, a Japanese explorer who led the 1910 Antarctic expedition.

Shirase’s surname, Kobuchizawa (小淵沢), is composed of 小 (ko), meaning “small,” 淵 (fuchi or buchi), meaning “deep pool” or “abyss,” and 沢 (sawa or zawa), meaning “swamp” or “marsh.”