"Gargoyle of Yoshinaga House" centers on the Yoshinaga family, who reside in a large, traditional Japanese house. The family consists of Futaba Yoshinaga, a high school student; her older sister, Chitose, a college student; and their father, a single parent. The household is unique due to the presence of two gargoyles, Gee and Ree, who serve as guardians of the house. These gargoyles are bound by a contract to protect the family and the residence, but their presence often leads to comedic and supernatural situations.

The gargoyles, Gee and Ree, are ancient beings with distinct personalities. Gee is more serious and dutiful, while Ree is playful and mischievous. Despite their differences, both are deeply loyal to the Yoshinaga family. Their interactions with the family members and the various visitors to the house drive much of the series' humor and plot development. The gargoyles' supernatural abilities, such as flight and transformation, are frequently used to resolve conflicts or create new ones, adding a layer of fantasy to the otherwise mundane domestic setting.

Futaba Yoshinaga, the younger sister, is a typical high school student who often finds herself caught between her studies and the antics of the gargoyles. Her older sister, Chitose, is more laid-back and often serves as a foil to Futaba's more serious demeanor. The father, while less prominent in the narrative, provides a grounding presence and occasionally mediates the chaos caused by the gargoyles.

The series explores themes of family, responsibility, and the blending of the supernatural with everyday life. The episodic nature of the story allows for a variety of scenarios, ranging from comedic misunderstandings to more heartfelt moments. The gargoyles' presence often leads to situations where the family must navigate both the ordinary challenges of life and the extraordinary circumstances brought about by their supernatural guardians.

Throughout the series, the relationship between the gargoyles and the Yoshinaga family evolves, highlighting the bonds of trust and mutual respect. The narrative maintains a light-hearted tone, with occasional moments of tension or drama, ensuring a balance between humor and emotional depth. The interplay between the human characters and the gargoyles creates a dynamic that is both entertaining and endearing, making "Gargoyle of Yoshinaga House" a distinctive blend of comedy, fantasy, and slice-of-life elements.