"Someday or One Day" is a Taiwanese drama series that blends elements of romance, mystery, and time travel. The story revolves around a woman named Han Shuo who, after losing her boyfriend, receives a mysterious cassette tape that transports her back to 1998. There, she encounters a man named Li Zi Wei, who bears a striking resemblance to her deceased partner. As the narrative unfolds, Han Shuo navigates the complexities of love and loss while trying to uncover the truth behind the time travel phenomenon. The series explores themes of fate, connection, and the impact of choices across different timelines.