"My Senpai Is Annoying" is a workplace romantic comedy set in a bustling office environment, centering on the dynamic between two colleagues. Futaba Igarashi, a petite and hardworking woman in her mid-20s, often feels overshadowed by her towering and boisterous senpai, Harumi Takeda. Despite his loud and overbearing demeanor, Takeda is a dependable and skilled employee who frequently supports Igarashi in her professional and personal life. Their interactions form the core of the series, blending humor with subtle romantic tension.

The narrative explores the daily lives of the office staff, highlighting the camaraderie and challenges of working in a corporate setting. Igarashi frequently finds herself frustrated by Takeda's teasing and larger-than-life personality, yet she gradually comes to appreciate his kindness and unwavering support. The series balances lighthearted moments, such as Takeda's playful antics and Igarashi's exasperated reactions, with quieter, more introspective scenes that reveal the depth of their growing bond.

Supporting characters add richness to the story, including Kazama, a reserved and perceptive colleague who often observes the interactions between Igarashi and Takeda, and Sakurai, a cheerful and energetic coworker who brings additional humor and warmth to the office dynamic. The series also touches on themes of self-confidence and personal growth, particularly through Igarashi's journey as she navigates her insecurities about her stature and professional abilities.

The episodic structure of the series allows for a variety of workplace scenarios, from handling demanding clients to organizing office events, all while maintaining a focus on the evolving relationship between Igarashi and Takeda. The blend of comedy, romance, and slice-of-life elements creates a relatable and engaging portrayal of modern office life, appealing to fans of lighthearted, character-driven narratives.