Nanako is the eldest of the three Okajima sisters in the anime Only Yesterday. In the flashback sequences set in 1966, she is portrayed as a university student attending art college, a detail that places her firmly within the burgeoning youth culture of mid-1960s Japan. She is often seen wearing fashionable clothes, such as mini-skirts, and is an enthusiastic fan of the Beatles, reflecting her engagement with contemporary trends. Her personality is generally more sophisticated and composed than those of her younger sisters, Yaeko and Taeko, though she still participates in the typical bickering that occurs among siblings. Despite this, she is notably kinder to Taeko than the middle sister Yaeko is. Nanako’s presence in the childhood segments highlights the age gap and the different stages of life the sisters occupy—while Nanako is moving toward adulthood, Taeko remains a child. In the present-day timeline of 1982, Nanako is married and living in the city, and she maintains a close, supportive relationship with the adult Taeko. The film uses Nanako’s character to illustrate the passage of time and the different paths the sisters have taken since their youth. Her role in the story is primarily that of a supporting figure, offering a contrast to Taeko’s more introspective and uncertain nature and serving as a benchmark for the growth and change that Taeko experiences throughout her journey. Nanako does not undergo a personal development arc of her own; instead, her character remains relatively static, representing the familial background against which Taeko’s memories and present decisions are measured. She does not possess any notable special abilities, as her significance lies in her relational and thematic function within the narrative.