"You're My Pet" centers on Sumire Iwaya, a career-driven woman in her late twenties who works as a journalist. Her life takes an unexpected turn when she discovers her former ballet classmate, Takeshi "Momoru" Gouda, living on the streets. Momoru, once a promising ballet dancer, has fallen on hard times and is now homeless. Feeling a mix of pity and nostalgia, Sumire offers him a place to stay in her apartment. However, their arrangement quickly evolves into an unconventional dynamic: Sumire decides to keep Momoru as her "pet," treating him as a domesticated companion rather than an equal.

The relationship between Sumire and Momoru is complex and layered. Sumire, who struggles with emotional vulnerability and maintaining personal relationships, finds solace in the simplicity of caring for Momoru. In return, Momoru, who is emotionally dependent and childlike in his demeanor, provides her with companionship and a sense of control. Their bond is tested as Momoru begins to regain his confidence and independence, while Sumire grapples with her own feelings of loneliness and the societal pressures of her career.

Throughout the series, secondary characters add depth to the narrative. Hasumi, Sumire's colleague and love interest, becomes a rival for her affections, creating tension in her relationship with Momoru. Meanwhile, Momoru's interactions with others, including his former ballet peers, reveal his struggles with identity and self-worth. The story explores themes of dependency, personal growth, and the blurred lines between caretaking and control.

As the series progresses, Sumire and Momoru's relationship evolves from a master-pet dynamic to a more nuanced connection. Sumire begins to confront her own emotional barriers, while Momoru starts to reclaim his sense of purpose. The narrative delves into their individual journeys of self-discovery, highlighting the challenges of navigating human relationships and the complexities of emotional intimacy. The story balances moments of humor and lightheartedness with deeper explorations of vulnerability and personal transformation.