Takahiro Takahashi is Misaki Takahashi's older brother, ten years his senior. He possesses a handsome appearance with black or dark blue hair swept to the right, grey eyes, and round-shaped glasses. Takahiro's personality is defined by extreme naivety and obliviousness, particularly concerning his close friend Akihiko Usami's longstanding romantic feelings, which he never acknowledges. Fundamentally kind-hearted, he cares deeply for those close to him, especially his younger brother Misaki. This protective instinct led him to sacrifice his own aspirations, dropping out of college to work and raise Misaki after their parents died in a car accident when Misaki was eight; Takahiro himself described his parenting approach as "very overprotective."

Takahiro maintains a strong bond with Misaki throughout the series, though their relationship faces challenges. Takahiro initially introduced Misaki to Akihiko to tutor him and improve his academic performance. Later, Takahiro expressed concern that Misaki living with Akihiko might foster excessive dependency. This concern sparked an argument where Takahiro pressured Misaki to find independent housing, though his wife, Manami Kajiwara, advised him to respect Misaki's autonomy and consider his perspectives as an adult.

Takahiro married Manami Kajiwara, and they have a son named Mahiro. Due to Takahiro's job, the family relocated to Osaka, prompting Misaki to move in with Akihiko. Takahiro eventually discovered Misaki and Akihiko's romantic relationship shortly before Misaki intended to reveal it, witnessing an intimate moment. His initial reaction showed neither explicit approval nor rejection. He later confronted Akihiko, punching him but not strongly opposing the relationship; instead, he issued a stern warning against hurting Misaki.

Takahiro remains a doting brother, frequently concerning himself with Misaki's happiness despite reassurances. His friendship with Akihiko dates back to high school, though Takahiro's naivety prevented him from recognizing Akihiko's earlier romantic feelings. They continue their friendship through regular phone calls even after Misaki moves in. Takahiro's role as a father to Mahiro further illustrates his familial devotion, though Akihiko notably dislikes the child due to discomfort around "creatures ruled by instinct."

Name trivia indicates "Takahiro" combines characters meaning "valuable" or "filial piety" (taka) and "big, great" or "prosperous" (hiro), while his surname "Takahashi" means "tall, high" (taka) and "bridge" (hashi). His name was originally "Kyoukou" before being changed to Takahiro.