Touko Nanami presents herself as a confident, dependable, and outgoing individual. She is highly determined and, at times, stubborn when it comes to achieving her goals, refusing to let anything or anyone dissuade her once she sets her mind to something. Her poised and capable exterior makes her well-respected among her peers, especially in her role as student council president.

However, beneath this self-assured image, Touko struggles with deep-seated insecurities and feelings of isolation. She obsessively hides any sign of weakness, preventing her from forming genuine emotional connections with those around her. While she appears extroverted and self-confident, she experiences profound loneliness and pressure to maintain an idealized version of herself. The belief that she must never fail or falter weighs heavily on her, reinforcing her fear of vulnerability.

Touko’s struggles stem from a long-standing effort to replace her late sister, Mio Nanami, whom she idolized. Over time, she internalized the belief that neither her achievements nor her relationships truly belonged to her, as she saw herself as merely a reflection of Mio. This mindset led her to feel unworthy of love and kindness, distancing herself from others out of fear that any change in her behavior would cause people to stop caring for her. She views love as conditional, believing she must remain a certain way to be accepted.

The only person she allows to see her true self is Yuu Koito. Touko believes that her love for Yuu is the one thing in her life that is genuinely hers. However, she initially insists that Yuu not fall in love with her, unknowingly forcing Yuu to suppress her own growing feelings. When Touko realizes the pain this has caused Yuu, she becomes ashamed of how much she has hurt her.

Following a heartfelt conversation, where they both openly confess their love for each other, Touko finally begins to let go of her fears. She comes to understand that love does not require a person to remain unchanging, and she gradually accepts that she does not have to be perfect to be loved.

Touko Nanami has long, straight black hair with bangs that fall to the right side of her face. She has grey eyes and a refined appearance that draws frequent admiration from those who meet her. Many people comment on her striking beauty, which, combined with her composed and elegant presence, contributes to her popularity at Tohmi Higashi High School.

As a child, Touko Nanami was withdrawn and quiet, often seen hiding behind her older sister, Mio Nanami. In contrast, Mio seven years her senior was a model student, well-liked by her peers, and the center of attention at her high school.

Mio’s sudden death in a traffic accident deeply impacted Touko. From that moment on, she became determined to emulate her late sister, suppressing her own personality and striving to live up to Mio’s legacy. Believing she had to take her sister’s place, Touko devoted herself to academics and athletics, excelling in both while adopting a confident and charismatic persona. Her efforts earned her widespread admiration from her peers and teachers, but at the cost of her own sense of self.

Determined to fulfill what Mio could not, Touko closely followed in her sister’s footsteps attending the same high school and joining the student council, just as Mio had seven years before.

The name Touko (燈子) is composed of “tou” (燈) meaning “light” and “ko” (子) meaning “child,” which can be interpreted as “child of light.” Her surname Nanami (七海) combines “nana” (七) meaning “seven” and “mi” (海) meaning “sea” or “ocean,” possibly symbolizing depth and vastness.