"Sing 'Yesterday' for Me" is a slice-of-life romance anime that explores the complexities of relationships, personal growth, and the passage of time. The narrative centers on Rikuo Uozumi, a recent college graduate working a mundane part-time job at a convenience store. Rikuo's life takes a turn when he reconnects with Haru Nonaka, a free-spirited and enigmatic woman who frequents the store and harbors feelings for him. Their interactions are marked by a mix of awkwardness and genuine connection, as Rikuo struggles to reconcile his own insecurities with Haru's straightforward affection.

Parallel to this, Rikuo's past resurfaces through his reunion with Shinako Morinome, a former classmate and the object of his unrequited love. Shinako, now a high school teacher, carries emotional baggage from a tragic event in her youth, which complicates her ability to fully reciprocate Rikuo's feelings. The dynamic between Rikuo, Haru, and Shinako forms the core of the story, as each character navigates their own emotional struggles and the evolving relationships between them.

The series delves into themes of unfulfilled dreams, the weight of past regrets, and the uncertainty of the future. Rikuo's journey is one of self-discovery, as he grapples with his lack of direction and the pressure to conform to societal expectations. Haru's carefree demeanor masks her own vulnerabilities, while Shinako's reserved nature reflects her internal conflict between moving forward and clinging to the past. Supporting characters, such as Rou Hayakawa, a younger student with a crush on Shinako, add further layers to the narrative, highlighting the generational and emotional divides between the characters.

The pacing of the story is deliberate, emphasizing the quiet, everyday moments that shape the characters' lives. The anime avoids melodrama, instead opting for a grounded portrayal of human emotions and relationships. Through its nuanced character interactions and realistic depiction of life's uncertainties, "Sing 'Yesterday' for Me" offers a poignant exploration of love, loss, and the passage of time.