Komachi Hikigaya is characterized by her cheerful, energetic, and occasionally scatterbrained nature. Unlike her older brother Hachiman, who is known for his cynical and socially detached outlook, Komachi is sociable, outgoing, and emotionally expressive. Though she can be forgetful once admitting she ate a gift meant for Hachiman without telling him she is also intelligent and perceptive, particularly when it comes to social interactions. While Hachiman often refers to her as an “idiot” in an academic sense, he acknowledges her emotional intelligence and strategic thinking.

Komachi frequently relies on her brother’s old schoolwork and seeks his help with studying. She also enjoys teasing Hachiman, especially by trying to orchestrate situations that bring him closer to Yui Yuigahama or Yukino Yukinoshita. She often sets up scenarios resembling dates or romantic encounters to subtly push him toward social engagement. Although she believes her brother is oblivious to her schemes, Hachiman is usually aware and attempts to avoid them much to Komachi’s frustration.

Hachiman has referred to Komachi as possessing the “Big Three”: cuteness, prettiness, and good looks. Her natural charm makes her well-liked at school, and despite being the sister of a notably unpopular older brother, she maintains a good reputation. While she is described as popular, her only explicitly shown friend is Taishi Kawasaki.

Komachi is compassionate and considerate, as seen when she requested help from the Service Club on Taishi’s behalf and when she volunteered to assist children during the Chiba summer camp. Despite her optimistic disposition, she shares several core traits with Hachiman, such as emotional intelligence, situational awareness, and an underlying desire to help others even if they mask it differently. Both are capable of reading between the lines and acting decisively when necessary.

Though typically upbeat, Komachi can become serious or even cold when genuinely hurt. One example involves her refusing to speak to her father for reasons not revealed, which deeply upset him. Similarly, she temporarily stopped talking to Hachiman after he was rude to her, only reconciling once he sincerely apologized and asked for advice.

In the light novels, it is noted that she often spends her weekends at home with Hachiman. Aware of the strengths and weaknesses of both social interaction and solitude, Komachi is selective about when, where, and with whom she chooses to engage demonstrating a mature understanding of social dynamics.

Komachi Hikigaya is a middle school student of average height with medium-length black hair. A notable feature of her hairstyle is an ahoge, a single strand of hair that sticks up mirroring her brother Hachiman’s own. Unlike Hachiman’s sharp and often cynical gaze, Komachi’s eyes are warm, lively, and expressive, reflecting her cheerful personality.

She is typically seen wearing her middle school uniform. However, beginning in Season 3, Episode 12 of the anime, she transitions to wearing the standard girls’ uniform of Sōbu High School, indicating her advancement to high school.

Komachi Hikigaya is a skilled cook, often preparing meals for both herself and her brother, Hachiman. Her cooking abilities are notably showcased in the OVA, and she is well-attuned to Hachiman’s preferences, knowing exactly what he likes and dislikes in both food and people.

In addition to her domestic skills, Komachi is highly perceptive particularly when it comes to her brother’s behavior. She is able to intuit when Hachiman has experienced a “social suicide” moment, even without being present. Her attentiveness and understanding of Hachiman’s needs are acknowledged by others in the series, including Yukino Yukinoshita, who comments on Komachi’s deep familiarity with her brother’s habits and well-being.

The given name Komachi (小町) is composed of the kanji ko (小), meaning “small,” and machi (町), meaning “town.” The name can evoke a sense of charm and simplicity, fitting for her cheerful and approachable personality.

Her surname, Hikigaya (比企谷), is made up of the kanji hi (比), meaning “ratio” or “compare,” ki (企), meaning “enterprise” or “scheme,” and ya (谷), meaning “valley.” While the full surname does not have a specific common meaning, it follows the naming convention typical in Japanese family names that combine natural and conceptual elements.