Hatoko is a central character in the third episode of the anime series. She is a single, working woman who is approaching her fortieth birthday, an age that serves as a significant point of reflection and anxiety for her. Her full name is Hatoko Nikawa.

Hatoko's personality is outwardly easygoing, and her story is told with a light, comical tone that complements her disposition. However, beneath this surface lies a deeper struggle with a mid-life crisis and a pronounced inferiority complex. A key aspect of her character is a habit of reflecting on her "best ten" moments, the most significant and memorable events of her life. To her disappointment, she realizes that despite being thirty-nine years old, every single one of these top ten memories occurred before her eighteenth birthday. This realization underscores her feeling that the most meaningful parts of her life are behind her and that she has not accomplished anything worthwhile in her adult years, a sentiment that contributes to her personal crisis.

The primary motivation for Hatoko throughout her story is a yearning to recapture the happiness of her past. This desire is focused on a chance to reconnect with her middle school ex-boyfriend, a young man who dumped her unceremoniously after only three weeks of dating. When she receives an invitation to a class reunion, she eagerly seizes upon it as an opportunity to see him again, hoping to rekindle the feelings associated with her youth and her first kiss. Her role in the narrative is as a protagonist who must confront the often harsh and disappointing gap between the idealized memories of her past and the realities of the present. She has a vivid imagination that frequently creates scenarios out of sync with reality, which is a key source of both humor and pathos as she builds up expectations that will likely be challenged.

Her key relationships are defined by the past. The most significant is with the boy from middle school, whose memory she has held onto for over twenty years. Her former classmates at the reunion serve as a mirror, showing her how much people, including herself and her ex, have changed over the decades. In her present life, she is shown dealing with feelings of alienation and a sense that nobody takes her seriously, which highlights her lack of meaningful present-day connections. Throughout her story, Hatoko engages in heavy drinking as a coping mechanism for her dissatisfaction and loneliness, a notable behavior that is portrayed frankly. Her development involves navigating the reunion and its aftermath, leading to a potential shift in her understanding of her own history and identity, as the sharp contrast between her cherished memories and the present reality forces a moment of reckoning. Her notable abilities are not physical or professional, but psychological: a powerful and vivid imagination that creates hopeful, romantic scenarios, and a reflexive tendency to catalogue and revisit her own past through her "best ten" framework.