"Mayoi Neko Overrun!" is a manga series that revolves around Takumi Tsuzuki, a high school student who lives and works at Stray Cats, a struggling confectionery shop run by his adoptive older sister, Otome. The shop is on the verge of closure due to financial difficulties, and Takumi’s life is further complicated when a mysterious girl named Nozomi Kiriya appears. Nozomi, who claims to be a stray cat, is taken in by Otome, adding to the chaos of Takumi’s daily life.

The narrative expands with the introduction of Fumino Serizawa, a wealthy and domineering classmate of Takumi who harbors feelings for him but struggles to express them. Fumino’s attempts to assert her dominance often lead to comedic misunderstandings and conflicts, particularly with Nozomi, who becomes a rival for Takumi’s attention. Another key character is Chise Umenomori, a shy and reserved girl who works at Stray Cats and has a quiet affection for Takumi. Her gentle demeanor contrasts with the more assertive personalities of Nozomi and Fumino.

The story blends slice-of-life elements with romantic comedy, focusing on the interactions and relationships between the main characters. The central theme revolves around the idea of "strays"—both literal and metaphorical—as the characters navigate their personal struggles and connections. Nozomi’s mysterious past and her claim of being a stray cat serve as a recurring motif, symbolizing the characters’ search for belonging and identity.

As the series progresses, the dynamics between Takumi, Nozomi, Fumino, and Chise evolve, with moments of humor, tension, and emotional growth. The confectionery shop, Stray Cats, acts as a central setting where many of the key events unfold, providing a backdrop for the characters’ interactions. The manga explores themes of family, friendship, and love, often through lighthearted and comedic scenarios, while occasionally delving into more serious and introspective moments.

The plot is driven by the characters’ relationships and their efforts to overcome personal challenges, whether it be Takumi’s responsibility to help save Stray Cats, Nozomi’s search for her place in the world, or Fumino’s struggle to reconcile her feelings with her pride. The series maintains a balance between comedy and heartfelt moments, creating a narrative that is both entertaining and emotionally engaging.