"Mokke" is a supernatural anime series that centers around the lives of two sisters, Shizuru and Mizuki, who possess the ability to see spirits and otherworldly entities. Shizuru, the older sister, is calm and mature, often acting as a protector for Mizuki, who is more impulsive and emotionally sensitive. Their unique abilities lead them to encounter various yokai, spirits, and supernatural phenomena, which they navigate with the guidance of their grandfather, a knowledgeable and experienced exorcist.

The narrative unfolds in a rural Japanese setting, where the sisters live with their grandparents after their parents decide it is safer for them to be away from the city due to their spiritual sensitivities. The grandfather, who is well-versed in folklore and traditional practices, teaches the sisters how to coexist with the spirits they encounter, emphasizing respect and understanding rather than fear or hostility. The grandmother, though less involved in the spiritual aspects, provides a grounding presence and emotional support for the family.

Throughout the series, Shizuru and Mizuki face a variety of supernatural challenges, ranging from benign encounters with mischievous yokai to more dangerous confrontations with malevolent spirits. Each episode typically presents a self-contained story, often drawing from Japanese folklore and mythology, while also developing the characters and their relationships. The sisters' differing personalities and approaches to dealing with the supernatural create a dynamic interplay, with Shizuru often relying on logic and caution, while Mizuki tends to act on instinct and emotion.

The series explores themes of family, tradition, and the coexistence of the human and spirit worlds. It balances moments of tension and mystery with lighter, more heartwarming scenes, reflecting the everyday lives of the characters amidst the extraordinary events they experience. The interactions between the sisters and their grandparents highlight the importance of familial bonds and the transmission of knowledge across generations.

As the story progresses, the sisters grow more adept at handling the supernatural, learning to trust each other and their own abilities. The series maintains a focus on the sisters' personal development and their evolving understanding of the spirit world, without delving into overarching plotlines or complex mythologies. Instead, it offers a series of episodic adventures that showcase the richness of Japanese folklore and the resilience of the human spirit in the face of the unknown.