Megumi Takahashi is a second-year high school student and the childhood best friend of Mari Tamaki, having known her since kindergarten. She has chest-length dark brown hair that she often styles in a fishtail braid resting on her right shoulder, light brown eyes, and wears round-shaped glasses. Her appearance is typically neat and orderly, which reflects her studious and serious demeanor.

In terms of personality, Megumi presents herself as a calm, rational, and observant individual. She tends to have a blunt way of speaking and can come across as somewhat cold or distant. She is not comfortable with things that are considered traditionally girly or frivolous, preferring a more pragmatic and detached perspective on situations. This outward composure, however, masks a more complex and emotionally vulnerable interior.

Megumi's motivations and sense of self-worth are deeply intertwined with her relationship with Mari. For years, she has defined herself by being the reliable, protective advisor to her less practical best friend. This dynamic gave her a sense of purpose and superiority, as caring for Mari and receiving praise for it became a core part of her identity. Her primary motivation is to maintain this role, and she struggles significantly when that foundation is threatened.

Her key relationship is, without question, with Mari Tamaki, whom she affectionately calls Kimari. This friendship is complex and somewhat codependent, with Megumi believing that Mari cannot function without her guidance. She also knows Shirase Kobuchizawa before Mari befriends her and initially holds a poor impression of her. While her interactions with Hinata Miyake and Yuzuki Shiraishi are more indirect, she does spend time with Hinata and Shirase at a karaoke bar before the Antarctic expedition, an event that contributes to her personal breakthrough.

Megumi's role in the story is to serve as a counterpoint to the main adventure, representing the comfort and stagnation of the past that Mari must leave behind. Initially, she is a supportive figure, regularly giving Mari advice and even offering to cover for her if she skipped school. However, when Mari decides to pursue her dream of going to Antarctica without first seeking Megumi's approval, the dynamic shatters. Feeling threatened and adrift, Megumi reacts with jealousy and tries to sabotage the trip by spreading rumors, informing Mari's mother about the plan, and telling the other girls about the money they had saved.

This leads to the most significant part of her character development. Upon realizing the harm she has caused, Megumi experiences a profound crisis of identity. In a tearful confession to Mari the morning of the departure, she admits that she has been the one clinging to their friendship, using Mari's dependence on her as a crutch because she had nothing else of her own. To break this unhealthy pattern, she declares their friendship over. This act is not one of malice but a painful step toward self-reliance. Mari, however, refuses to accept the end of their bond, hugging her and reaffirming their friendship before leaving.

Megumi continues to grow even in Mari's absence. She maintains contact via social media during the Antarctica trip. In the final moments of the story, she demonstrates the full extent of her development by embarking on her own adventure to the Arctic, showing that she has finally found a purpose and identity independent of Mari. A notable ability of Megumi is her skill in observing situations and analyzing her own emotions, even if she is initially overwhelmed by feelings of guilt and jealousy. This self-awareness ultimately becomes the tool she uses to initiate her personal transformation.